As of September 30, 2024, the Company’s stock incentive plans included the 2010 Stock Plan (the "2010 Plan"), the 2020 Equity Incentive Plan (the "2020 Plan"), the 2021 Inducement Equity Incentive Plan, as amended (the "2021 Plan"), and the 2022 Equity Incentive Plan, as amended (the "2022 Plan") (together, the "Plans").

The 2022 Plan provides for the award of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, other stock-based awards, and cash-based awards to employees, directors, consultants or advisors. Shares of common stock subject to outstanding awards granted under the 2020 Plan and the 2010 Plan that expire, terminate, or are otherwise surrendered, cancelled, forfeited, or repurchased by the Company are available for issuance under the 2022 Plan.

The 2021 Plan provides for the award of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards to persons who were not previously an employee or director of the Company or who are commencing employment with the Company following a bona fide period of non-employment, in either case, as an inducement material to such person’s entry into employment with the Company and in accordance with the requirements of the Nasdaq Stock Market Rule 5635(c)(4). Neither consultants nor advisors are eligible to participate in the 2021 Plan.

The 2020 Plan provided for the award of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards to employees, directors, consultants or advisors. As of June 15, 2022, the effective date of the 2022 Plan, no further awards will be made under the 2020 Plan. Any options or awards outstanding under the 2020 Plan are governed by the terms of the 2020 Plan.

The 2010 Plan provided for the granting of incentive stock options and nonstatutory stock options to employees, directors, consultants or advisors. As of the effective date of the 2020 Plan, no further awards will be made under the 2010 Plan. Any options or awards outstanding under the 2010 Plan are governed by the terms of the 2010 Plan.

As of September 30, 2024 and December 31, 2023, there were 6,360,189 and 3,472,195 shares available for grant under the Plans, respectively. The following table presents classification of stock-based compensation expense within the unaudited condensed consolidated statements of operations:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Cost of sales	$	1,238	$	1,234	$	3,733	$	3,922
Research and development	4,218		4,101		12,512		11,422
Sales and marketing	971		914		2,913		2,705
General and administrative	5,971		6,405		18,266		17,258
Total stock-based compensation	$	12,398	$	12,654	$	37,424	$	35,307

Each restricted stock unit (“RSU”) represents the right to receive one share of the Company’s common stock upon vesting. The fair value of RSUs granted by the Company was calculated based upon the Company’s closing stock price on the date of the grant, and the stock-based compensation expense is recognized over the vesting period. RSUs generally vest over four years with 25% of the grants vesting at the end of the first year and the remaining vesting annually over the following three years.

There were 28,195, 1,217,503, 33,285, and 748,265 RSUs granted during the three and nine months ended September 30, 2024 and 2023, respectively. The weighted average grant date fair value for each RSU granted during the three and nine months ended September 30, 2024 and 2023 was $20.88, $24.92, $41.08, and $26.07, respectively.

As of September 30, 2024, there was $35,031 of unrecognized compensation cost related to RSUs granted under the Plans, which is expected to be recognized over a weighted average period of 3.12 years. During the three and nine months ended September 30, 2024 and 2023, 7,910, 220,518, 1,166, and 13,241 RSUs vested, respectively. The fair value of RSUs vested during the three and nine months ended September 30, 2024 and 2023 was $177, $5,632, $62, and $355, respectively.

In March 2024 and February 2023, the Company awarded performance-based restricted stock units ("PRSUs") under the 2022 Plan. Each PRSU represents a contingent right to receive one share of common stock upon the achievement of specified performance goals. The fair value of PRSUs granted by the Company was calculated based upon the Company's closing stock price on the date of the grant, and the stock-based compensation expense is recognized when the grant date is determined and performance conditions are probable of achievement. At the point where performance conditions are considered probable of achievement, the Company records stock-based compensation expense with a cumulative catch-up expense in the period first recognized and on a straight-line basis over the remaining period for which the performance criteria are expected to be completed.

In March 2024, the Company awarded to all executive officers PRSUs for a maximum of 180,000 shares (based on 150% achievement of the applicable performance conditions outlined in the awards), with a target award of 120,000 PRSUs (based on 100% achievement of the applicable performance conditions), and a threshold award of 60,000 PRSUs (based on 50% achievement of the applicable performance conditions). All such PRSUs were considered granted under ASC 718, Compensation—Stock Compensation ("Topic 718") in March 2024. Such PRSUs are scheduled to vest, if at all, upon the certification by the Company's compensation committee of the achievement of the applicable performance conditions following the filing of the Company's Annual Report on Form 10-K for the fiscal year ending December 31, 2026.

In February 2023, the Company awarded to certain executive officers PRSUs for a maximum of 62,693 shares (based on 150% achievement of the applicable performance conditions outlined in the awards), with a target award of 41,795 PRSUs (based on 100% achievement of the applicable performance conditions), and a threshold award of 20,898 PRSUs (based on 50% achievement of the applicable performance conditions). All such PRSUs were considered granted under Topic 718 in February 2023. Such PRSUs are scheduled to vest, if at all, upon the certification by the Company's compensation committee of the achievement of the applicable performance conditions following the filing of the Company's Annual Report on Form 10-K for the fiscal year ending December 31, 2025.

In August 2022, the Company awarded 90,000 PRSUs to an executive officer of which 30,150 PRSUs were considered granted under Topic 718 at the time the PRSUs were awarded. In March 2024 and 2023, of the 90,000 PRSUs awarded in August 2022, an additional 14,850 and 45,000 PRSUs were considered granted under Topic 718, respectively. During the three months ended March 31, 2024, the Company's compensation committee determined the achievement of the awards set to vest upon the certification by the Company's compensation committee following the filing of the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2023. Of the 36,000 PRSUs that were eligible to vest, the Company's compensation committee determined that the applicable performance conditions had been met for 9,000 of the PRSUs, which vested during the three months ended March 31, 2024, and that the applicable performance conditions had not been met for 27,000 PRSUs, which were forfeited during the three months ended March 31, 2024. The remaining 54,000 PRSUs are scheduled to vest, if at all, upon the certification by the Company's

The weighted average grant date fair value for each PRSU granted during the three and nine months ended September 30, 2024 and 2023 was zero, $26.08, zero, and $22.48, respectively. During the three and nine months ended September 30, 2024, zero and 9,000 PRSUs vested, respectively. No PRSUs vested during the three and nine months ended September 30, 2023.

Stock options must be granted at an exercise price not less than 100% of the fair market value per share at the grant date. The board of directors or compensation committee determines the exercise price of the Company’s stock options based on the closing price of the common stock as reported on the Nasdaq Global Select Market on the date of the grant. The maximum contractual term of options granted under the Plans is typically 10 years, options generally vest over four years with 25% of the shares underlying the option vesting at the end of the first year and the remaining vesting monthly over the following three years. In March 2024 and February 2023, the Company granted the chief executive officer premium priced options to purchase 87,271 and 65,525 shares of common stock, respectively, with exercise prices equal to 110% of the closing price of the Company's common stock on the date of grant.

The fair value of each option award is determined on the date of grant using the Black Scholes Merton option-pricing model. The calculation of fair value included several assumptions that require management’s judgment. The expected terms of options granted to employees during 2024 and 2023 were calculated using an average of historical exercises. Estimated volatility for the nine months ended September 30, 2024 and 2023 incorporated a calculated volatility derived from the historical closing prices of shares of common stock of similar entities whose share prices were publicly available for the expected term of the option. The risk-free interest rate was based on the U.S. Treasury constant maturities in effect at the time of grant for the expected term of the option. The Company accounts for forfeitures as they occur; as such, the Company does not estimate forfeitures at the time of grant.

The weighted average grant date fair value per share of options granted during the three and nine months ended September 30, 2024 and 2023 was $11.24, $14.90, $24.75, and $15.99, respectively. The intrinsic value of options exercised during the three and nine months ended September 30, 2024 and 2023 was $676, $2,125, $2,835, and $14,140, respectively.

As of September 30, 2024, there was $49,625 of unrecognized compensation cost related to unvested stock options granted under the Plans, which is expected to be recognized over a weighted average period of 2.15 years. The fair value of shares vested during the three and nine months ended September 30, 2024 and 2023 was $8,125, $31,763, $9,991, and $37,858, respectively.