The 2013 Stock Incentive Plan ("2013 Plan") provides for the grant of any or all of the following types of awards: (a) stock options, (b) restricted stock, (c) deferred stock, (d) stock appreciation rights, and (e) other stock-based awards including restricted stock units. Awards under the 2013 Plan may be granted singly, in combination, or in tandem. Subject to standard anti-dilution adjustments as provided, the 2013 Plan provides for an aggregate of 2,600,000 shares of the Company's common stock to be available for distribution. The Company's Compensation Committee generally has the authority to administer the 2013 Plan, determine participants who will be granted awards, the size and types of awards, the terms and conditions of awards and the form and content of the award agreements representing awards. Awards under the 2013 Plan may be granted to employees, directors and consultants of the Company and its subsidiaries. As of December 31, 2017, there are 1,253,099 shares of common stock available for issuance under the 2013 Plan.

During the year ended December 31, 2017, the Company granted 13,500 restricted stock units ("RSUs") under the 2013 Plan to each of its three non-management directors as an annual grant for 2017 for service on the Company's Board of Directors. Each RSU represented a contingent right to receive one share of the Company's common stock. The RSUs vested in four equal quarterly installments of 3,375 shares of common stock on March 15, 2017, June 15, 2017, September 15, 2017 and December 15, 2017, subject to continued service on the Board of Directors.

During the year ended December 31, 2016, the Company granted 15,000 RSUs under the 2013 Plan to each of its three non-management directors. The RSUs vested 7,500 shares of common stock on March 9, 2016 (the date of grant) and 3,750 shares on September 9, 2016 and December 9, 2016, subject to continued service on the Board of Directors.

On June 9, 2016, the Company also granted 50,000 RSUs under the 2013 Plan to each of its Chief Financial Officer and Executive Vice President, and 40,000 RSUs to a consultant to the Company. Each such RSUs vested 50% on the one year anniversary of grant (June 9, 2017) and will vest 50% on the two year anniversary of grant (June 9, 2018), subject to continue service to the Company.

In July 2016, the Company granted to the Chairman and Chief Executive Officer, under its 2013 Plan, 750,000 RSUs (each RSU awarded by the Company represents a contingent right to receive one share of the Company's common stock) which vest in three tranches, as follows: (i) 250,000 RSUs shall vest on July 14, 2018, subject to the Chairman and Chief Executive's continued employment by the Company through the vesting date (the "Employment Condition"); (ii) 250,000 RSUs shall vest at any time beginning July 14, 2018 through July 14, 2021 in equal annual installments for the remaining term of employment, subject to (1) the Employment Condition being satisfied through each such annual vesting date and (2) the Company's common stock achieving a closing price (for 20 consecutive trading days) of a minimum of $3.25 per share (subject to adjustment for stock splits) at any time during the term of employment; and (iii) 250,000 RSUs vest at any time beginning July 14, 2018 through July 14, 2021 in equal annual installments for the remaining term of employment subject to (1) the Employment Condition being satisfied through each such annual vesting date and (2) the Company's common stock achieving a closing price (for 20 consecutive trading days) of a minimum of $4.25 per share (subject to adjustment for stock splits) at any time during the term of employment. The aforementioned stock price vesting conditions of $3.25 per share and $4.25 per share have been satisfied. Notwithstanding the aforementioned, in the event of a Change of Control (as defined), a Termination Other Than for Cause (as defined), or a termination of employment for Good Reason (as defined), all of the 750,000 RSUs shall accelerate and become immediately fully vested. All RSUs granted by the Company to its officers, directors or consultants have dividend equivalent rights.

The effect of a market condition is reflected in the estimate of the grant-date fair value of the restricted stock units utilizing a Monte Carlo valuation technique. The service period for restricted stock units with a market-based vesting condition is inferred from the application of the Monte Carlo valuation technique. Assumptions utilized in connection with the Monte Carlo valuation technique included estimated risk-free interest rate ranging from 0.67% to 1.10%; expected volatility of 38.8% and the expected dividend yield was based on expectations regarding dividend payments at the time of grant.

All of the Company's issued and RSUs have dividend equivalent rights. As of December 31, 2017, there was $84,000 accrued for dividend equivalent rights.

A summary of restricted stock units granted during the year ended December 31, 2017 is as follows (each restricted stock unit represents the contingent right to receive one share of the Company's common stock):

Restricted stock unit compensation expense was $949,000 for the year ended December 31, 2017 and $497,000 for the year ended December 31, 2016.

The Company has an aggregate of $860,000 of unrecognized restricted stock unit compensation expense as of December 31, 2017 to be expensed over a weighted average period of 1.58 years.

At December 31, 2017, stock options to purchase an aggregate of 385,000 shares of common stock were outstanding under the 2013 Plan and options to purchase 1,625,000 shares of common stock were outstanding representing option grants outside of the 2013 Plan (issued prior to the establishment of the 2013 Plan). There were no grants of stock options during the years ended December 31, 2017 and December 31, 2016.

The following table summarizes stock option activity for the years ended December 31:

During the year ended December 31, 2017 and December 31, 2016, the Company did not grant any stock options. During the year ended December 31, 2017, the Company did not recognize any stock-based compensation related to the vesting of prior issued stock options to employees and directors. During the year ended December 31, 2016, the Company recognized stock-based compensation of $12,000 related to the issuance of stock options and vesting of prior issued options. The Company at December 31, 2017 and 2016 has no remaining unrecognized expenses related to unvested stock options to employees and directors. The aggregate intrinsic value of all stock options exercisable at December 31, 2017 was $2,245,550.

During the year ended December 31, 2017, stock options to purchase an aggregate of 300,000 shares of the Company's common stock were exercised (50,000 shares of which were exercised on a net exercise (cashless) basis), by a former director of the Company (125,000 shares), the Company's Chief Financial Officer and his three children (an aggregate of 75,000 shares), and two directors of the Company (each 50,000 shares) at exercise prices ranging from $1.14 to $1.40 per share. With respect to the aforementioned stock option to purchase 50,000 shares exercised on a net exercise (cashless) basis by a director of the Company, net shares of 26,734 were delivered to the director.

During the year ended December 31, 2016, stock options to purchase an aggregate of 530,000 shares of common stock were exercised (470,251 of which were exercised on a net exercise (cashless) basis), by the Company's Chief Financial Officer (100,000 shares), Executive Vice President (240,000 shares), a director (75,000 shares), a consultant (90,000 shares) and a former director (25,000 shares), at prices ranging from $1.21 to $1.60 per share. With respect to the aforementioned stock option exercises on a net exercise (cashless) basis, aggregate net shares of 132,080 were delivered to the Chief Financial Officer (43,580 shares), Executive Vice President (23,944 shares), director (47,283) and a consultant (17,273 shares).

The following table presents information relating to all stock options outstanding and exercisable at December 31, 2017:

As of December 31, 2017, there were no outstanding warrants to purchase shares of the Company's common stock. As of December 31, 2016, the following are the outstanding warrants to purchase shares of the Company's common stock:

2016

The outstanding warrants to purchase an aggregate of 375,000 shares of common stock at December 31, 2016 pertain to 5-year warrants issued to Recognition Interface, LLC in connection with the Company's (through Mirror Worlds Technologies, LLC, its wholly-owned subsidiary) purchase of the Mirror Worlds Patent Portfolio in May 2013 (See Note G[2]).

During the year ended December 31, 2016, Recognition Interface, LLC exercised warrants to purchase an aggregate of 375,000 shares of the Company's common stock at an exercise price of $1.40 per share resulting in gross proceeds to the Company of $525,000. In January 2017, Recognition Interface, LLC exercised warrants to purchase an additional 375,000 shares of the Company's common stock at an exercise price of $2.10 per share, resulting in additional gross proceeds to the Company of $787,500.