Stockholders' Equity (Tables)

6 Months Ended

Jun. 28, 2019

Stockholders Equity Note [Abstract]

Schedule of Compensation Cost

The cost that has been charged against income for stock-based compensation is set forth below (in thousands):

	Three Months Ended				Six Months Ended
	June 28, 2019		June 29, 2018		June 28, 2019		June 29, 2018
Employee stock options	$	2,162	$	897	$	3,592	$	1,516
Restricted stock		77		59		159		110
Restricted stock units		311		494		1,415		1,092
Nonemployee stock options		29		148		54		181
Total stock-based compensation expense	$	2,579	$	1,598	$	5,220	$	2,899

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

The Company recorded stock-based compensation costs in the following categories (in thousands):

	Three Months Ended				Six Months Ended
	June 28, 2019		June 29, 2018		June 28, 2019		June 29, 2018
Cost of sales	$	22	$	4	$	36	$	7
General and administrative		1,018		655		1,796		1,174
Marketing and selling		690		366		1,861		826
Research and development		849		573		1,527		892
Total stock-based compensation expense, net		2,579		1,598		5,220		2,899
Amounts capitalized as part of inventory		276		145		465		267
Total stock-based compensation expense, gross	$	2,855	$	1,743	$	5,685	$	3,166

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The risk-free rate is based on the U.S. Treasury yield curve corresponding to the expected term at the time of the grant.

	Three Months Ended						Six Months Ended
	June 28, 2019			June 29, 2018			June 28, 2019			June 29, 2018
Expected dividend yield		0	%		0	%		0	%		0	%
Expected volatility		53	%		53	%		53	%		53	%
Risk-free interest rate		2.05	%		2.81	%		2.41	%		2.70	%
Expected term (in years)		5.67			5.72			5.67			5.72

Schedule of Share-based Compensation, Stock Options, Activity

A summary of stock option activity under the Plan for the six months ended June 28, 2019 is presented below:

	Stock Options (in 000’s)			Minimum Exercise Price		Maximum Exercise Price
Outstanding at December 28, 2018		3,920
Granted		801
Exercised		(126	)
Forfeited or expired		(16	)
Outstanding at June 28, 2019		4,579		$	3.50	$	43.84
Exercisable at June 28, 2019		3,026

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

A summary of restricted stock and RSU activity under the Plan for the six months ended June 28, 2019 is presented below:

	Restricted Stock (in 000’s)			Restricted Stock Units (in 000’s)
Unvested at December 28, 2018		11			322
Granted		11			19
Vested		(11	)		(202	)
Forfeited or expired		—			(5	)
Unvested at June 28, 2019		11			134