The Company’s warrant liability arises as a result of the issuance of warrants exercisable in US dollars. As the denomination is different from the Canadian dollar functional currency of the entity issuing the underlying shares, the Company recognizes a derivative liability for these warrants and re-measures the liability at the end of each reporting period using the Black-Scholes model. Changes in respect of the Company’s warrant liability are as follows:

	December 31, 2020		December 31, 2019
Balance at beginning of the period	$	1,579	$	2,009
Fair value adjustment		650		(520	)
Effect of movement in exchange rates		66		90
Balance at end of the period	$	2,295	$	1,579

Continuity of warrants during the periods is as follows:

	Underlying Shares			Weighted Average Exercise Price
Warrants outstanding and exercisable, January 1, 2019		10,778,061			$1.20
Issued		464,122			C$0.85
Expired		(3,602,215	)		$1.99
Warrants outstanding and exercisable, December 31, 2019		7,639,968			$0.79
Exercised		(4,195,072	)		$0.80
Exercised		(464,122	)		C$0.85
Warrants outstanding and exercisable, December 31, 2020		2,980,774			$0.80

			All Warrants Outstanding and Exercisable
Expiry Date	Exercise Price per Share		December 31, 2020		December 31, 2019
July 30, 2020	C$	0.85		-		464,122
September 25, 2023	$	0.80		2,980,774		7,175,846
				2,980,774		7,639,968

As at December 31, 2020, the weighted average remaining contractual life of warrants outstanding was 2.73 years (December 31, 2019 - 3.55 years).

Valuation of the warrant liability requires the use of highly subjective estimates and assumptions including the expected stock price volatility. The expected volatility used in valuing warrants is based on volatility observed in historical periods. Changes in the underlying assumptions can materially affect the fair value estimates. The fair value of the warrant liability was calculated using the Black-Scholes model with the following weighted average assumptions and resulting fair values:

	December 31, 2020			December 31, 2019
Weighted average assumptions:
Risk-free interest rate		0.20	%		1.68	%
Expected dividend yield		0	%		0	%
Expected warrant life (years)		2.73			3.57
Expected stock price volatility		73.93	%		61.61	%
Weighted average fair value	$	0.77		$	0.22