Stock-based compensation

6 Months Ended

Jun. 30, 2022

Stock-based compensation

Stock-based compensation

9. Stock-based compensation

Stock-based compensation expense for all stock awards consists of the following (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Cost of product revenue	$	137	$	96	$	225	$	186
Cost of service and other revenue		205		122		371		232
Research and development		482		409		880		808
Selling, general, and administrative		4,362		3,023		7,537		5,810
Total	$	5,186	$	3,650	$	9,013	$	7,036

In both the three and six months ended June 30, 2022, the Company incurred approximately $0.7 million of stock-based compensation expense related to the transition of the Company’s former Chief Executive Officer to Executive Chairman in accordance with ASC Topic 718, Compensation - Stock Compensation. As of June 30, 2022, there was $46.4 million of total unrecognized compensation cost related to unvested restricted stock units (RSUs) and stock options, which is expected to be recognized over the remaining weighted-average vesting period of 2.9 years.