REVENUES

12 Months Ended

Dec. 31, 2022

Revenue from Contract with Customer [Abstract]

REVENUES

12. REVENUES

For each of the identified periods, revenues can be categorized into the following (in thousands): 

	Year Ended
	December 31,
	2022			2021
Product sales	$	20,347		$	8,574
Maintenance fees		53			44
Professional services		527			98
Shipping and handling		1,137			319
Discounts and allowances		(69	)		(33	)
Total revenues	$	21,995		$	9,002

During the year ended December 31, 2022 and 2021, 29% and 62% of revenues were derived from customers located in California, respectively. In addition, 9% of revenues in the year ended December 31, 2022 were international sales compared to none in the prior year.

At December 31, 2022 and 2021, deferred revenue was $1.4 million and $0.3 million, respectively. These amounts consisted mainly of customer deposits in the amount of $1.0 million and $0.1 million for December 31, 2022 and 2021, respectively and prepaid multi-year maintenance plans for previously sold products which account for $0.3 million and $0.2 million for December 31, 2022 and 2021, respectively, and pertain to services to be provided through 2028. Revenue recognized during the year ended December 31, 2022 which pertained to revenue deferred in prior years was $0.1 million and immaterial for the year ended December 31, 2021.