The Company adopted the 2008 Stock Plan (“2008 Plan”) under which it may issue stock options to purchase shares of common stock, and award restricted stock and stock appreciation rights to employees, Directors and consultants. The 2008 Plan expired in March 2018 and all award issuance therefore ceased. Options generally vest over a four-year period with a one-year cliff. The option term is no longer than five years for incentive stock options for which the grantee owns greater than 10% of the Company’s capital stock and no longer than 10 years for all other options. The Company has a repurchase option on unvested restricted stock exercisable upon the voluntary or involuntary termination of the purchaser’s employment with the Company for any reason. The Company’s repurchase right lapses in accordance with the vesting terms. During the three months ended March 31, 2024, there were no exercises of common stock options prior to the vesting of such options. Options outstanding under the 2008 Plan will remain outstanding until they are exercised, canceled or expire.

In May 2018, the Company adopted the 2018 Stock Plan (“2018 Plan”) under which the Company may issue stock options to purchase shares of common stock, and award restricted stock and stock appreciation rights to employees, Directors and consultants.

Under the 2018 Plan, the Board of Directors may grant incentive stock options or nonqualified stock options. Incentive stock options may only be granted to Company employees. The 2018 Plan expired in May 2023 and all award issuance therefore ceased. The exercise price of incentive stock options and non-qualified stock options cannot be less than 100% of the fair value per share of the Company’s common stock on the grant date. If an individual owns more than 10% of the Company’s outstanding capital stock, the price of each share incentive stock option will be at least 110% of the fair value. Fair value is determined by the Board of Directors. Options generally vest over a four-year period with a one-year cliff. The option term is no longer than five years for incentive stock options for which the grantee owns greater than 10% of the Company’s capital stock and no longer than 10 years for all other options. The Company has a repurchase option on unvested restricted stock exercisable upon the voluntary or involuntary termination of the purchaser’s employment with the Company for any reason. The Company’s repurchase right lapses in accordance with the vesting terms. Options outstanding under the 2018 Plan will remain outstanding until they are exercised, canceled or expire. During the three months ended March 31, 2024, there were no exercises of common stock options prior to the vesting of such options.

In May 2023, the Company adopted the 2023 Equity Incentive Plan (“2023 Plan”) under which the Company may issue stock options to purchase shares of common stock, award restricted stock, restricted stock units (“RSU”), dividend equivalents, stock appreciation rights, and other stock-based or cash-based awards to employees, Directors and consultants.

Through March 31, 2024, the Company has granted 1,097,901 stock options to purchase shares of common stock and 1,517,946 RSU’s under the 2023 Plan. The stock options generally vest over a four-year period, following the date of grant, with 25% vesting on the first anniversary of the grant date and the remaining vesting in equal monthly installments thereafter. As of March 31, 2024, 15,911 stock options granted under the 2023 Plan had vested and were exercisable. There have been no stock options exercised under the 2023 Plan. The RSUs generally vest over a three-year period, following the date of grant, with a third of the award vesting on each year on the annual anniversary of the grant date. During the three months ended March 31, 2024, the Company granted 685,213 RSUs to employees and executives pursuant to the 2023 Plan, which immediately vested into shares of Common Stock. As of March 31, 2024, 685,213 RSUs that were granted under the 2023 Plan have vested.

Collectively, the 2008 Stock Plan, 2018 Stock Plan and the 2023 Equity Incentive Plan are referred to as “the Plans”. The Company has authorized 9,189,613 shares of common stock to be issued under the Plans. The Company has reserved 5,905,424 shares of common stock for future issuance under the 2023 Plan.

The Company measures stock-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. The Company recorded stock-based compensation expense in the following expense categories in its accompanying condensed consolidated statements of operations and comprehensive loss:


	Three Months Ended March 31,
(in thousands)	2024		2023
Research and development	$	456	$	49
Sales and marketing		830		173
General and administrative		1,155		122
Cost of sales		64		22
Total stock-based compensation	$	2,505	$	366

The following table summarizes stock option activity for the Plans for the three months ended March 31, 2024:


	Number of shares			Weighted average exercise price per share		Weighted average remaining contractual term (years)		Aggregate intrinsic value (in 000's)
Outstanding at December 31, 2023		4,872,527		$	3.64		6.10
Granted		—		$	—
Exercised		(755,016	)	$	0.33
Forfeited		(83,150	)	$	4.85
Expired		(46,600	)	$	2.03
Outstanding at March 31, 2024		3,987,761		$	4.26		6.80	$	738
Exercisable at March 31, 2024		2,138,472		$	1.32		5.16	$	673
Vested and expected to vest at March 31, 2024		3,987,761		$	4.26		6.80

As of March 31, 2024, the total unrecognized compensation expense related to unvested stock option awards was $8.6 million, which the Company expects to recognize over a weighted-average period of 3.0 years.

The fair value of options is estimated using the Black-Scholes option pricing model, which takes into account inputs such as the exercise price, the value of the underlying common stock at the grant date, expected term, expected volatility, risk-free interest rate and dividend yield. The fair value of each grant of options was determined using the methods and assumptions discussed below.

There were no options granted during the three months ended March 31, 2024. The fair value of each stock option granted during the three months ended March 31, 2023 was estimated on the date of grant using the weighted average assumptions in the table below:

The following table summarizes RSU activity for the Plans for the three months ended March 31, 2024:


	Number of shares			Weighted average grant date fair value per share
Outstanding at December 31, 2023		872,037		$	11.27
Granted		685,213		$	1.35
Vested		(685,213	)	$	1.35
Forfeited		(39,304	)	$	9.39
Outstanding at March 31, 2024		832,733		$	11.36

As of March 31, 2024, the total unrecognized compensation expense related to unvested RSUs was $7.2 million, which the Company expects to recognize over a weighted-average period of 2.3 years.