Revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (i) identification of the contract with a customer; (ii) identification of the performance obligations in the contract; (iii) determination of the transaction price; (iv) allocation of the transaction price to the separate performance obligations in the contract; and (v) recognition of the revenue associated with performance obligations as they are satisfied. The Company applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price based on the estimated relative standalone-selling prices of the promised products or services underlying each performance obligation. The Company determines standalone-selling prices based on the price at which the performance obligation is sold separately. If the standalone-selling price is not observable through past transactions, the Company estimates the standalone-selling price considering available information such as market conditions and internally approved pricing guidelines related to the performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

When determining the transaction price of a contract, an adjustment is made if payment from a customer occurs either significantly before or significantly after performance, resulting in a significant financing component. Applying the practical expedient in paragraph ASC 606-10-32-18, the Company does not assess whether a significant financing component exists if the period between when the Company performs its obligations under the contract and when the customer pays is one year or less. The Company did not have any contracts outstanding at both December 31, 2020 and December 31, 2019 and did not enter into any contracts during each of the years ended December 31, 2021 and 2020 that contained a significant financing component.

The Company records deferred revenue for product sales when (i) the Company has delivered products but other revenue recognition criteria have not been satisfied or (ii) payments have been received in advance of the completion of required performance obligations.

Shipping and handling costs associated with outbound freight after control over a product has transferred to a customer are accounted for as fulfillment costs and are included in the cost of product revenue. The associated amount of revenue recognized includes the consideration to which the Company expects to be entitled to receive in exchange for incurring these shipping and handling costs.

The Company generally enters into contracts containing one type of performance obligation. The Company recognizes product revenue when the performance obligation is satisfied, which is generally upon delivery according to contractual shipping terms within customer purchase orders.

The Company also enters into rebate agreements with certain customers. These agreements may be considered an additional performance obligation of the Company or variable consideration within a contract. Rebates are recorded as a reduction of revenue in the period the related product revenue is recognized. A corresponding liability is recorded as a component of deferred revenue on the consolidated balance sheets. These arrangements are primarily based on the customer attaining contractually specified sales volumes.

The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized. The Company currently estimates product return liabilities using historical rates of return, current quarter credit sales, and specific items of exposure on a contract-by-contract basis. Sales return reserves were approximately $0.1 million at both December 31, 2021 and December 31, 2020. The Company recognized less than $0.1 in warranty expense related to the sale of EV thermal barriers during the year ended December 31, 2021.

The Company manufactures and sells subsea products that are designed for pipe-in-pipe applications in offshore oil production and are typically customized to meet customer specifications. Subsea products typically have no alternative use and contain an enforceable right to payment. Customer invoicing terms for subsea products are typically based on certain milestones within the production and delivery schedule. Under the provisions of ASC 606, the Company recognizes revenue at a point in time when transfer of control of the products is passed to the customer, or over time utilizing the input method. The timing of revenue recognition is assessed on a contract-by-contract basis. During the years ended December 31, 2021, 2020, and 2019 the Company recognized revenue of $4.7 million, $9.7 million, and $17.0 million respectively, in connection with subsea projects.

The Company supplies fabricated, multi-part thermal barriers for use in battery packs in the electric vehicle market. These thermal barriers are customized to meet customer specifications. Thermal barrier products typically have no alternative use and may contain an enforceable right to payment. Under the provisions of ASC 606, the Company may recognize revenue at a point in time when transfer of the control of the products is passed to the customer, or over time utilizing the input method. The timing of revenue recognition is assessed on a contract-by-contract basis. During the year ended December 31, 2021, the Company recognized revenue of $6.7 million in connection with thermal barrier contracts.

The Company performs research services under contracts with various government agencies and other institutions. These contracts generally have one type of performance obligation associated with the provision of research services including certain licenses to any resulting intellectual property. The Company records revenue using the percentage-of-completion method in two ways: (1) for firm-fixed-price contracts, the Company accrues that portion of the total contract price that is allocable on the basis of the Company’s estimates of costs incurred to date to total contract costs; and (2) for cost-plus-fixed-fee contracts, the Company records revenue that is equal to total payroll cost incurred times a stated factor plus reimbursable expenses, to a stated upper limit. The primary cost under the Company’s research service contracts is the labor expended in completing the research. Typically, the only deliverable, other than the labor hours expended, is reporting research results to the customer or delivery of research grade aerogel products. Because the input measure of labor hours expended is also reflective of the output measure, it is a reliable means to measure the extent of progress toward completion. Revisions in cost estimates and fees during the course of the contract are reflected in the accounting period in which the facts that require the revisions become known. Contract costs and rates used to allocate overhead to contracts are subject to audit by the respective contracting government agency. Adjustments to revenue as a result of audit are recorded within the period they become known. To date, adjustments to revenue as a result of contracting agency audits have been insignificant.

In the following tables, revenue is disaggregated by primary geographical region and source of revenue:

	December 31, 2021
	U.S.		International		Total
	(In thousands)
Geographical region
Asia	$	—	$	19,383	$	19,383
Canada		—		2,985		2,985
Europe		—		27,924		27,924
Latin America		—		4,493		4,493
U.S.		66,837		—		66,837
Total revenue	$	66,837	$	54,785	$	121,622

Source of revenue
Product revenue	$	59,789	$	49,960	$	109,749
Subsea projects		—		4,699		4,699
EV thermal barrier		6,538		126		6,664
Research services		510		—		510
Total revenue	$	66,837	$	54,785	$	121,622

	December 31, 2020
	U.S.		International		Total
	(In thousands)
Geographical region
Asia	$	—	$	38,403	$	38,403
Canada		—		986		986
Europe		—		13,881		13,881
Latin America		—		2,161		2,161
U.S.		44,842		—		44,842
Total revenue	$	44,842	$	55,431	$	100,273

Source of revenue
Product revenue	$	42,416	$	47,678	$	90,094
Subsea projects		1,987		7,753		9,740
Research services		439		—		439
Total revenue	$	44,842	$	55,431	$	100,273

	December 31, 2019
	U.S.		International		Total
	(In thousands)
Geographical region
Asia	$	—	$	44,485	$	44,485
Canada		—		9,064		9,064
Europe		—		24,081		24,081
Latin America		—		3,417		3,417
U.S.		58,328		—		58,328
Total revenue	$	58,328	$	81,047	$	139,375

Source of revenue
Product revenue	$	52,050	$	67,856	$	119,906
Subsea projects		3,837		13,191		17,028
Research services		2,441		—		2,441
Total revenue	$	58,328	$	81,047	$	139,375

The following table presents changes in the Company’s contract assets and contract liabilities during the year ended December 31, 2021:

	Balance at December 31, 2020		Additions		Deductions			Balance at December 31, 2021
	(In thousands)
Contract assets
Subsea projects	$	1,370	$	4,521	$	(4,443	)	$	1,448
Product revenue		—		362		(127	)		235
Research services		67		510		(429	)		148
Total contract assets	$	1,437	$	5,393	$	(4,999	)	$	1,831
Contract liabilities
Deferred revenue
Product revenue	$	1,859	$	3,686	$	(4,224	)	$	1,321
Subsea projects		178		2,168		(2,346	)		—
Prepayment liability		9,555		173		—			9,728
Total contract liabilities	$	11,592	$	6,027	$	(6,570	)	$	11,049

During the year ended December 31, 2021, the Company recognized $1.7 million of revenue that was included in deferred revenue at December 31, 2020.

A contract asset is recorded when the Company satisfies a performance obligation by transferring a promised good or service and has earned the right to consideration from its customer. These assets may represent a conditional or unconditional right to consideration and are included within accounts receivable on the consolidated balance sheets.

A contract liability is recorded when consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services under the terms of the contract. Contract liabilities are recognized as revenue after control of the products or services is transferred to the customer and all revenue recognition criteria have been met.