Restricted Share Units (“RSUs”). RSUs represent the right to receive unrestricted shares of the Company’s common stock at the time of vesting, subject to any restrictions as specified in the individual holder’s award agreement. RSUs are subject to graded vesting, generally ranging between one and four years and the fair value of the RSUs is equal to the Company’s common stock price on the date of grant. RSU activity for the three months ended March 31, 2022 is as follows (in thousands, except for weighted-average grant date fair value):


	Number of RSUs			Weighted-Average Grant Date Fair Value
Outstanding as of December 31, 2021		3,683		$	10.95
Granted		1,814			15.07
Vested and delivered		(1,433	)		10.28
Forfeited		(61	)		12.69
Outstanding as of March 31, 2022 (1)		4,003			13.03

(1)

Included in “Outstanding as of March 31, 2022” are 63 RSUs that were vested, but not yet delivered.

Performance Share Units (“PSUs”). PSUs represent the right to receive unrestricted shares of the Company’s common stock at the time of vesting. The fair value of the PSUs is equal to the Company’s common stock price on the date of grant. Expense related to PSUs is recognized when the performance conditions are probable of being achieved. The percentage of PSUs that shall vest will range from 0% to 200% of the number of PSUs granted based on the Company’s future performance related to certain revenue and adjusted earnings before interest, income taxes, depreciation and amortization targets over a three-year performance period. These PSUs are subject to cliff vesting at the end of the respective performance period. PSU activity for the three months ended March 31, 2022 is as follows (in thousands, except for weighted-average grant date fair value):


	Number of PSUs			Weighted-Average Grant Date Fair Value
Outstanding as of December 31, 2021		142		$	23.98
Granted		275			15.07
Vested and delivered		(142	)		23.98
Forfeited		—			—
Outstanding as of March 31, 2022		275			15.07

Stock Options. Stock options represent the right to purchase shares of the Company’s common stock at the time of vesting, subject to any restrictions as specified in the individual holder’s award agreement. Stock options are subject to three-year cliff vesting and expire 10 years from the grant date. Stock option activity for the three months ended March 31, 2022 is as follows (in thousands, except for weighted-average grant date fair value and weighted-average remaining contractual term):


	Number of Options		Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Outstanding as of December 31, 2021		804	$	5.27		8.58	$	5,754
Granted		263		9.39		—		—
Vested and delivered		—		—		—		—
Forfeited		—		—		—		—
Outstanding as of March 31, 2022		1,067		6.28		8.73		4,634
Exercisable as of March 31, 2022		—		—		—		—

The fair value of the stock options granted during the three months ended March 31, 2022 and March 31, 2021 are estimated on the grant date using the Black-Scholes option pricing model, using the following assumptions:


	2022			2021
Risk-free interest rate		2.21	%		1.15	%
Weighted-average volatility		65.22	%		69.00	%
Dividend yield		0	%		0	%
Expected years until exercise		6.5			6.5