We compensate officers, directors, key employees and consultants with stock-based compensation under the Image Sensing Systems, Inc. 2005 Stock Incentive Plan (the "2005 Plan") and the Image Sensing Systems, Inc. 2014 Stock Option and Incentive Plan (the "2014 Plan"), both of which were approved by our shareholders and are administered under the supervision of our Board of Directors. Although stock options granted under the 2005 Plan are still outstanding, the 2005 Plan expired, and the Company can no longer grant options or other awards under the 2005 Plan. Stock option awards are granted at exercise prices equal to the closing price of our stock on the day before the date of grant. Generally, options vest ratably over periods of three to five years from the dates of the grant, beginning one year from the date of grant, and have a contractual term of nine to 10 years.

Compensation expense, net of estimated forfeitures, is recognized ratably over the vesting period. Stock-based compensation expense included in general and administrative expense for the three-month periods ended September 30, 2019 and 2018 was $58,000 and $41,000, respectively. Stock-based compensation expense included in general and administrative expense for the nine-month periods ended September 30, 2019 and 2018 was $162,000 and $164,000, respectively. At September 30, 2019, 186,622 shares were available for grant under the Company's 2014 Plan.

A summary of the stock option activity for the first nine months of 2019 is as follows:

	Number of Shares			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Options outstanding at December 31, 2018		39,000		$	6.26		2.80	$	4,480
Granted		—		$	—		—	$	—
Exercised		(1,000	)	$	4.22		—	$	950
Expired		(18,000	)	$	8.19		—	$	—
Forfeited		(4,000	)	$	4.22		—	$	3,360

Options outstanding at September 30, 2019		16,000		$	4.73		4.20	$	4,903
Options exercisable at September 30, 2019		16,000		$	4.73		4.20	$	4,903

There were no stock options and stock options to purchase 1,000 shares exercised during the three and nine-month periods ended September 30, 2019, respectively, and no stock options exercised in the three- and nine-month periods ended September 30, 2018. During the nine-month period ended September 30, 2019, we recognized no stock-based compensation expense related to stock options compared to $1,000 recognized during the nine-month period ended September 30, 2018. As of September 30, 2019, there was no unrecognized compensation cost related to non-vested stock options.

Restricted stock awards are granted under the 2014 Plan at the discretion of the Compensation Committee of our Board of Directors. We issue restricted stock awards to executive officers and key consultants. These awards may contain certain performance conditions or time-based vesting criteria. The restricted stock awards granted to executive officers vest if the various performance or time-based metrics are met. Stock-based compensation is recognized for the number of awards expected to vest at the end of the period and is expensed beginning on the grant date through the end of the vesting period. At the time of vesting of the restricted stock awards, the recipients of common stock may request to receive a net of the number of shares required for employee withholding taxes, which can be withheld up to the relevant jurisdiction's maximum statutory rate.

We also issue stock awards as a portion of the annual retainer for each director on a quarterly basis. The stock awards are fully vested at the time of issuance. Compensation expense related to any stock awards issued to employees is determined on the grant date based on the publicly-quoted fair market value of our common stock and is charged to earnings on the grant date.

The following table summarizes restricted stock award activity for the first nine months of 2019:

	Number of Shares			Weighted Average Grant Date Fair Value
Awards outstanding December 31, 2018	58,877		$	3.22
Granted	52,120			5.02
Vested	(40,210	)		3.99
Forfeited	(11,826	)		3.04
Awards outstanding at September 30, 2019	58,961		$	4.32

As of September 30, 2019, the total stock-based compensation expense related to non-vested awards not yet recognized was $204,000, which is expected to be recognized over a weighted average period of 2.2 years. During the nine-month periods ended September 30, 2019 and September 30, 2018, we recognized $162,000 and $163,000, respectively, of stock-based compensation expense related to restricted stock awards.