13.  STOCK-BASED COMPENSATION

The Company’s 2006 Stock Option Plan (“2006 Plan”) provides for the grant of incentive stock options and nonqualified stock options for the purchase of up to an aggregate of 1,125,000 shares of the Company’s common stock by officers, employees and directors of the Company. Under the terms of the plan, incentive stock options may be granted to employees at an exercise price per share of not less than the fair value per common share on the date of the grant (not less than 110% of the fair value in the case of holders of more than 10% of the Company’s voting stock). Nonqualified stock options may be granted at the discretion of the Company’s Board of Directors. The maximum term of an option may not exceed 10 years, and options become exercisable at such times and in such installments as determined by the Board of Directors. No awards have been granted under the 2006 Plan.

The Company's 2011 Equity Incentive Plan (“2011 Plan”) provides for the grant of up to an aggregate of 1,000,000 shares of restricted stock, restricted share units, stock appreciation rights, dividend or dividend equivalent rights, stock awards and other awards valued in whole or in part by reference to or otherwise based on the Company’s common stock, to officers, employees and directors of the Company. The 2011 Plan was approved by the Company’s shareholders at the 2012 Annual Meeting. At December 31, 2016, 526,762 shares remained available to be issued through the 2011 Plan. Compensation cost is measured at the date of the grant and is recognized in earnings over the period in which the shares vest. Restricted stock expense for the twelve months ended December 31, 2016, January 2, 2016, and December 27, 2014 totaled $3,676, $3,254 and $2,961, respectively.

The following table summarizes restricted stock activity for the years ended December 31, 2016, January 2, 2016, and December 27, 2014:

The Company had $1,924 of total unrecognized compensation cost related to restricted stock awards granted under the 2011 Plan as of December 31, 2016. That cost is expected to be recognized over a weighted average period of 0.74 years.

The Company maintains an Employee Stock Purchase Plan (“ESPP”), in which only Sun Hydraulics US employees are eligible to participate. Employees in the United States who choose to participate are granted an opportunity to purchase common stock at 85 percent of market value on the first or last day of the quarterly purchase period, whichever is lower. Employees in the United Kingdom, under a separate plan, are granted an opportunity to purchase common stock at market value, on the first or last day of the quarterly purchase period, whichever is lower, with the Company issuing one additional free share of common stock for each six shares purchased by the employee under the ESPP. The ESPP authorizes the issuance, and the purchase by employees, of up to 1,096,875 shares of common stock through payroll deductions. No U.S. employee is allowed to buy more than $25 of common stock in any year, based on the market value of the common stock at the beginning of the purchase period, and no U.K. employee is allowed to buy more than the lesser of £1.5 or 10% of his or her annual salary in any year. Employees purchased 33,956 shares at a weighted average price of $25.95, and 34,053 shares at a weighted average price of $29.94, under the ESPP during the twelve months ended December 31, 2016, and January 2, 2016, respectively. The Company recognized $312, $199 and $173 of compensation expense during the twelve months ended December 31, 2016, January 2, 2016, and December 27, 2014, respectively. At December 31, 2016, 585,384 shares remained available to be issued through the ESPP and the U.K. plan.

In March 2012, the Board of Directors adopted the Sun Hydraulics Corporation 2012 Nonemployee Director Fees Plan (the “2012 Directors Plan”), which was approved by the shareholders of the Company at its 2012 annual meeting. Under the 2012 Directors Plan as initially adopted, as compensation for attendance at each Board meeting and each meeting of each committee of the Board on which he or she serves when the committee meeting is not held within one day of a meeting of the Board, each Nonemployee Director was paid 500 shares of Common Stock. The Chairman’s fee was twice that of a regular director, and the fee for the chairs of each Board committee is 125% that of a regular director. In February 2015, the board adopted amendments to the 2012 Directors Plan which revised the compensation for Nonemployee Directors. Each Nonemployee director now receives an annual retainer of 2,000 shares of Common Stock. The Chairman's retainer is twice that of a regular director, and the retainer for the chairs of each Board Committee is 150% that of a regular director. In addition, each Nonemployee Director receives 250 shares of Common Stock for attendance at each Board meeting and each meeting of each committee of the Board on which he or she serves when the committee meeting is not held within one day of a meeting of the Board. In June 2015, the Company's shareholders approved the amendments to the 2012 Directors Plan.

The Board has the authority to change from time to time, in any manner it deems desirable or appropriate, the share compensation to be awarded to all or any one or more Nonemployee Directors, provided that, with limited exceptions, such changes are subject to prior shareholder approval. The aggregate number of shares which may be issued during any single calendar year is limited to 25,000 Shares. The 2012 Directors Plan authorizes the issuance of up to 270,000 shares of common stock. At December 31, 2016, 174,874 shares remained available for issuance under the 2012 Directors Plan. Directors were granted 24,500 and 24,375 shares for the twelve months ended December 31, 2016, and January 2, 2016, respectively. The Company recognized director stock compensation expense of $831, $829, and $677 for the twelve months ended December 31, 2016, January 2, 2016, and December 27, 2014, respectively.