The Amended and Restated Omnibus Equity Incentive Plan (“the Plan”) provides for various forms of stock-based incentives. To date, of the available forms of awards under the Plan, the Company has granted only stock options, restricted stock, unrestricted share grants, RSUs and PSUs. Options under the Plan are granted at fair market value on the date of grant, become exercisable generally over a three-year period, or as determined by the Board of Directors, and expire over periods not exceeding 10 years from the date of grant. Certain option and share awards provide for accelerated vesting if there is a change in control and pre-established financial metrics are met (as defined in the Plan). Grants of restricted stock outstanding under the Plan generally vest over periods of one to three years. Grants of RSUs and PSUs outstanding under the Plan generally vest based on service, performance, or a combination of both. On July 30, 2020, stockholders approved a proposal to increase the number of shares under the Plan by 2,650,000 shares, for a total of 18,035,000 shares. As of January 1, 2021, there were 3,380,231 shares available for grant under the Plan.

The Company recognized a net income tax benefit in the Consolidated Statements of Income for stock-based compensation expense for incentive stock options and non-qualified stock options, as a result of disqualifying dispositions and exercises, respectively. The Company does not recognize deferred income taxes for incentive stock option compensation expense, and records a tax deduction only when a disqualified disposition has occurred (see Note 10).

The following table represents the fair value of stock-based compensation granted during the year ended 2020 (in thousands):

The Company recorded stock-based compensation expense by award as follows (in thousands):

	Years Ended
	2020		2019		2018
Employee stock option	$	9,577	$	8,144	$	4,013
Restricted stock		428		320		274
Restricted stock units		1,732		1,905		2,120
Performance stock units		147		—		—
Nonemployee stock options		262		178		355
Total stock-based compensation expense	$	12,146	$	10,547	$	6,762

The Company recorded stock-based compensation expense in the following categories (in thousands):

	Years Ended
	2020		2019		2018
Cost of sales	$	112	$	52	$	15
General and administrative		4,925		4,010		2,635
Selling and marketing		3,471		3,318		1,805
Research and development		3,638		3,167		2,307
Total stock-based compensation expense, net		12,146		10,547		6,762
Amounts capitalized as part of inventory		1,129		1,017		637
Total stock-based compensation expense, gross	$	13,275	$	11,564	$	7,399

As of January 1, 2021, total unrecognized compensation cost related to non-vested stock-based compensation arrangements granted under the Plan were as follows (in thousands):

This cost is expected to be recognized over a weighted-average period of approximately two years.

The fair value of each option award is estimated on the date of grant using a Black-Scholes option valuation model applying the weighted-average assumptions noted in the following table. Expected volatilities are based on historical volatility of the Company’s stock. The expected term of options granted is derived from the historical exercises and post-vesting cancellations, and represents the period of time that options granted are expected to be outstanding. The Company has calculated an 6% estimated forfeiture rate based on historical forfeiture experience. The risk-free rate is based on the U.S. Treasury yield curve corresponding to the expected term at the time of the grant.

	Years Ended
	2020			2019			2018
Expected dividend yield		0	%		0	%		0	%
Expected volatility		53	%		53	%		53	%
Risk-free interest rate		0.53	%		2.40	%		2.71	%
Expected term (in years)		5.72			5.66			5.72

A summary of option activity under the Plan for the year ended January 1, 2021 is presented below:

	Shares (in 000’s)			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in 000’s)
Outstanding at January 3, 2020		4,326		$	16.46
Granted		621			28.78
Exercised		(1,507	)		13.70
Forfeited or expired		(22	)		32.35
Outstanding at January 1, 2021		3,418		$	19.80		6.60	$	203,087
Exercisable at January 1, 2021		2,372		$	15.05		5.66	$	152,218

A summary of unvested options activity under the Plan for the year ended January 1, 2021 was as follows:

	Shares (in 000’s)			Weighted-Average Grant-Date Fair Value
Unvested at January 3, 2020		1,279		$	15.44
Granted		621			13.85
Forfeited or expired		(22	)		16.52
Vested		(832	)		14.66
Unvested at January 1, 2021		1,046		$	15.09

The weighted average grant date fair value of options granted and the total intrinsic value of options exercised were as follows:

	Years Ended
	2020		2019		2018
Weighted-average grant-date fair value	$	13.85	$	17.95	$	11.95
Intrinsic value of options (in thousands)	$	59,771	$	9,955	$	13,699

A summary of restricted stock, RSU and PSU activity under the Plan for the year ended January 1, 2021was as follows:

	Restricted Stock					Restricted Stock Units					Performance Stock Units
	Units (in 000’s)			Weighted- Average Grant- Date Fair Value		Units (in 000’s)			Weighted- Average Grant- Date Fair Value		Units (in 000’s)		Weighted- Average Grant- Date Fair Value
Outstanding at January 3, 2020		11		$	29.39		104		$	10.79		—	$	—
Granted		11			58.25		127			33.57		15		51.42
Vested		(11	)		29.82		(108	)		12.52		—		—
Forfeited or expired		—			—		(1	)		13.80		—		—
Outstanding at January 1, 2021		11		$	59.06		122		$	32.97		15	$	51.42

On August 10, 2018, the Company closed an offering of its common stock. As part of this transaction, the Company issued 1,999,850 shares of its common stock at a price of $36.309 per share. Net proceeds, after deducting expenses, received from this offering were $72,150,000.