On May 16, 2018, our shareholders approved our 2018 Stock Option and Stock Incentive Plan (the “2018 Plan”), which supersedes our 2008 Stock Option and Stock Incentive Plan (the “2008 Plan”). Under the terms of the 2018 Plan, our Board of Directors may grant up to 1,200,000 shares of common stock in the form of shares of restricted stock, restricted stock units, stock appreciation rights, stock options, or combinations thereof, to officers, directors, employees, consultants and advisors. Grants under the 2018 Plan must be made within ten years of the date the Plan was approved. Stock options are exercisable upon the terms set forth in each grant agreement, but in no event more than ten years from the date of grant. Restricted stock and restricted stock units vest in accordance with the terms set forth in each applicable award agreement. At June 27, 2020, 856,921 shares were available for grant under the 2018 Plan.

Vesting of restricted stock and RSU awards is conditional based on continued employment or service for a specified period and, in certain circumstances, the attainment of performance goals. With respect to restricted stock and RSU awards, we retain the shares underlying the award, and any dividends paid thereon, until the vesting conditions have been met. For time-based restricted stock and RSU awards, compensation cost related to the stock is recognized on a straight-line basis over the vesting period and is calculated using the closing price per share of our common stock on the grant date. For performance-based restricted stock and RSU awards tied to growth in adjusted pre-tax income, compensation cost related to the award is recognized over the performance period and is calculated using the closing price per share of our common stock on the grant date and an estimate of the probable outcome of the performance conditions at each reporting date. Since 2019, we have granted performance-based restricted stock and RSU awards that vest based on our total shareholder return ranking relative to the S&P Mid-Cap 400 Growth Index over a three-year performance period. For performance-based restricted stock and RSU awards tied to total shareholder return, compensation cost related to the award is recognized on a straight-line basis over the performance period and is calculated using the simulated fair value per share of our common stock based on the application of a Monte Carlo simulation model. Compensation cost related to restricted stock and RSU awards was $1.1 million and $0.8 million for the thirteen weeks ended June 27, 2020 and June 29, 2019, respectively, and $2.0 million and $1.5 million for the twenty-six weeks ended June 27, 2020 and June 29, 2019, respectively. The compensation costs were classified as selling, general and administrative expense in the Consolidated Statements of Operations.

The following table summarizes our restricted stock and RSU award activity for the twenty-six weeks ended June 27, 2020:

	Shares			Weighted Average Price
Balance at December 28, 2019		177,491		$	76.70
Granted		80,580		$	62.45
Vested		(17,408	)	$	65.41
Cancelled		(23,823	)	$	78.04
Balance at June 27, 2020		216,840		$	72.16

As of June 27, 2020, there was $9.6 million of unrecognized compensation cost related to unvested restricted stock and RSU awards that is expected to be recognized over a weighted-average period of approximately 2.7 years.

Cash flows resulting from tax deductions in excess of the tax effect of compensation cost recognized in the financial statements are classified as operating cash flows. The excess tax benefit generated from restricted stock and RSU awards that vested was less than $0.1 million and $0.2 million in the twenty-six weeks ended June 27, 2020 and June 29, 2019, respectively, and was credited to income tax expense.

We expense the grant-date fair value of stock options. Compensation cost is recognized on a straight-line basis over the vesting period for which related services are performed. The compensation cost charged against income was $0.3 million and $0.2 million for the thirteen weeks ended June 27, 2020 and June 29, 2019, respectively, and $0.5 million and $0.3 million for the twenty-six weeks ended June 27, 2020 and June 29, 2019, respectively. The compensation costs were classified as selling, general and administrative expense in the Consolidated Statements of Operations. No cost was capitalized during the twenty-six weeks ended June 27, 2020 or June 29, 2019.

We use the Black-Scholes option valuation model to estimate the fair value of stock options granted. Expected volatility and expected dividend yield are based on the actual historical experience of our common stock. The expected life represents the period of time that options granted are expected to be outstanding and was calculated using historical option exercise data. The risk-free rate was based on a U.S. Treasury security with terms equal to the expected time of exercise as of the grant date. During the twenty-six weeks ended June 27, 2020 and June 29, 2019, we granted 102,584 and 36,235 stock options, respectively.

The following table summarizes our stock option activity for the twenty-six weeks ended June 27, 2020:

	Shares			Weighted Average Exercise Price		Weighted Average Remaining Term (In years)		Aggregate Intrinsic Value
Balance at December 28, 2019		181,712		$	70.78
Granted		102,584		$	61.96
Forfeited		(4,728	)	$	67.27
Exercised		(419	)	$	72.55
Balance at June 27, 2020		279,149		$	67.60		4.9	$	928,794
Options exercisable at June 27, 2020		105,038		$	65.30		2.3	$	702,837

There were options to purchase 419 and 34,301 shares of common stock exercised during the twenty-six weeks ended June 27, 2020 and June 29, 2019, respectively. As of June 27, 2020, there was $3.6 million of unrecognized compensation cost related to unvested stock options that is expected to be recognized over a weighted-average period of 3.1 years.

There was no cash received from stock option exercises in the twenty-six weeks ended June 27, 2020. Cash received from stock option exercises was less than $0.1 million in the twenty-six weeks ended June 29, 2019.

There was no excess tax benefit generated from stock options exercised in the twenty-six weeks ended June 27, 2020 or June 29, 2019.

In May 2017, our shareholders approved the Dorman Products, Inc. Employee Stock Purchase Plan (the “ESPP”), which made available up to 1,000,000 shares of our common stock for sale to eligible employees. The purpose of the ESPP, which is qualified under Section 423 of the Internal Revenue Service Code of 1986, as amended, is to encourage stock ownership through payroll deductions and limited cash contributions by our employees. These contributions are used to purchase shares of the Company’s common stock at a 15% discount from the lower of the market price at the beginning or end of the purchase window. There were 10,735 shares purchased under the ESPP plan in both the thirteen and twenty-six weeks ended June 27, 2020, and 13,669 shares purchased in both the thirteen and twenty-six weeks ended June 29, 2019. During both the thirteen weeks ended June 27, 2020 and June 29, 2019, compensation cost under the ESPP was $0.1 million. During both the twenty-six weeks ended June 27, 2020 and June 29, 2019, compensation cost under the ESPP was $0.2 million.