Accrued Warranty (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2021

Dec. 31, 2020

Product Warranties Disclosures [Abstract]

Schedule of Warranty Accrual Included in Accrued Expenses

Activity in the warranty accrual is included in accrued expenses in the condensed balance sheets and consisted of the following (in thousands):

	Nine Months Ended September 30, 2021			Year Ended December 31, 2020
Balance at beginning of period	$	204		$	234
Increase in warranty accrual		—			19
Change in liability for pre-existing warranties		—			4
Claims satisfied		(9	)		(53	)
Total accrued warranty	$	195		$	204

Activity in the product warranty accrual is included in accrued expenses above and consists of the following (in thousands):

	Year ended December 31,
	2020			2019
Balance at beginning of period	$	234		$	50
Increase in warranty accrual		19			709
Change in liability for pre-existing warranties		4			(28	)
Claims satisfied		(53	)		(497	)
Accrued warranty	$	204		$	234