The Company uses the Black-Scholes option pricing model to estimate the grant date fair value of its stock options. There was no income tax benefit recognized in the financial statements for share-based compensation arrangements for the three months ended March 31, 2021 and 2020.

There were 616 stock options granted during the three months ended March 31, 2021. There were no stock options granted during the three months ended March 31, 2020. The assumptions underlying the calculation of grant date fair value per share for the three months ended March 31, 2021 are as follows:

	For the Three Months Ended March 31,
	2021
Number of options granted		616
Weighted-average expected volatility	114.3%
Weighted-average risk-free interest rate		1.19	%
Weighted-average expected option term (in years)		6.25
Weighted-average dividend yield		—	%
Weighted-average fair value per share of grants	$	4.17

The stock price volatility for the Company’s options was determined using a blend of the Company’s historical volatility since its initial public offering in June 2017 and the historical volatilities for industry peers. The risk-free interest rate was derived from U.S. Treasury rates existing on the date of grant for the applicable expected option term. The expected term represents the period of time that options are expected to be outstanding. Because the Company has only very limited historical exercise behavior, it determines the expected life assumption using the simplified method, which is an average of the contractual term of the option and its ordinary vesting period. The expected dividend yield assumption is based on the fact that the Company has never paid, nor has any intention to pay, cash dividends.

As of March 31, 2021, there were 266,031 shares available for issuance under the Myomo, Inc. 2018 Stock Option and Incentive Plan (the “2018 Plan”). On January 1, 2021, the number of shares reserved and available for issuance under the 2018 Plan increased by 183,726 shares pursuant to a provision in the 2018 Plan that provides that the number of shares of common stock reserved and available for issuance under the 2018 Plan will be cumulatively increased each January 1 by 4% of the number shares of common stock outstanding on the immediately preceding December 31 or such lesser number of shares of common stock determined by management in consultation with members of the Board of Directors, including the compensation committee.

Awards of restricted stock units may be net share settled upon vesting to cover the required employee statutory withholding taxes and the remaining amount is converted into shares based upon their share-value on the date the award vests. These payments of employee withholding taxes are presented in the statements of cash flows as a financing activity.

The Company accounts for stock awards to employees and non-employees based upon the fair value of the award on the date of grant. The fair value of that award is then ratably recognized as expense over the period during which the recipient is required to provide services in exchange for that award.

The Company attributes the value of stock-based compensation to operations on the straight-line method such that the expense associated with awards is evenly recognized over the vesting period.

The Company recognized stock-based compensation expense related to the issuance of stock option awards, restricted stock awards and restricted stock units to employees, non-employees and directors in the statements of operations as follows:

	Three Months Ended
	March 31,
	2021		2020
Cost of goods sold	$	9,033	$	5,859
Research and development		47,403		13,883
Selling, general and administrative		109,535		103,467
Total	$	165,971	$	123,209

As of March 31, 2021, there was approximately $117,500 of unrecognized compensation cost related to unvested stock options that is expected to be recognized over a weighted-average period of 2.03 years.

As of March 31, 2021, there was approximately $3,000 of unrecognized compensation cost related to unvested restricted stock awards that is expected to be recognized over a weighted-average period of 0.37 years.

As of March 31, 2021, there was approximately $972,200 of unrecognized compensation expense related to unvested restricted stock units that is expected to be recognized over a weighted-average period of 2.36 years.