Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2021

Stockholders' Equity Note [Abstract]

Schedule of activity under the stock option plans

	2010 Plan			2017 Plan			Weighted Average Exercise Price		Aggregate Intrinsic Value(1)
Outstanding as of December 31, 2019		255,000			133,500		$	6.48	$	(516,475	)
Grants		7,000			93,000		$	5.03
Terminations/forfeitures		(12,000	)		(50,000	)	$	5.45
Exercises		(12,500	)		—		$	3.15
Outstanding as of December 31, 2020		237,500			176,500		$	6.38	$	(180,038	)
Grants		—			72,000		$	9.79
Terminations/forfeitures		(7,000	)		(12,000	)	$	6.49
Exercises		(7,000	)		(18,000	)	$	7.08
Outstanding as of June 30, 2021		223,500			218,500		$	6.90	$	1,150,755
Vested as of June 30, 2021		183,500			84,500		$	6.72	$	746,280
Vested and expected to vest as of June 30, 2021		223,500			218,500		$	6.90	$	1,150,755
Reserved for future grants		—			63,500

⁽¹⁾ Intrinsic value is the difference between the fair market value of the underlying common stock as of the date indicated and as of the date of the option grant (which is equal to the option exercise price).

Schedule of additional information about the stock option plans

	Number of Shares		Weighted Average Fair Value at Grant Date		Weighted Average Exercise Price
Non-vested stock options as of January 1, 2021		248,000	$	3.25	$	6.44
Non-vested stock options as of June 30, 2021		174,000	$	3.40	$	7.18
Stock options granted during the six-month period ended June 30, 2021		72,000	$	4.41	$	9.79
Stock options that vested during the six-month period ended June 30, 2021		127,000	$	3.68	$	7.32
Stock options that were forfeited during the six-month period ended June 30, 2021		19,000	$	3.41	$	6.49

Schedule of fair value stock option grant using black-scholes option valuation model with the weighted-average assumptions

	During the Three-Month Periods Ended June 30,						During the Six-Month Periods Ended June 30,
	2021			2020			2021			2020
Risk-free interest rate		0.90	%		0.29	%		0.86	%		0.54	%
Dividend yield		0	%		0	%		0	%		0	%
Expected volatility		54	%		50	%		54	%		51	%
Expected life		4.6 years			4.8 years			4.8 years			5.6 years