The Company leases office space and equipment under agreements classified as operating leases that expire on various dates through 2023. The Company’s most significant active leases as of September 30, 2020 are for office and manufacturing space in Tucson, Arizona, which expire in 2021. The Company also leases a development laboratory space in San Carlos, California, which expires in 2023. The Company’s leases do not include any contingent rental payments, impose any financial restrictions, or contain any residual value guarantees. Certain of the Company’s leases include renewal options and escalation clauses; renewal options have not been included in the calculation of the lease liabilities and right-of-use assets as the Company is not reasonably certain to exercise the options. Annual rent increases are included in the calculation of the operating lease right-of-use assets. Variable expenses generally represent the Company’s share of the landlord’s operating expenses and are recorded when incurred. Incremental borrowing rates used to discount future lease payments in calculating lease liabilities were estimated by reference to the rate on the Company’s existing debt, as this represents the cost of borrowing for secured loans of similar duration. The Company does not have any operating lease arrangements where it acts as a lessor.

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Operating leases
Operating lease cost	$	182,287	$	174,581	$	570,163	$	435,312
Variable lease cost		36,554		36,210		89,716		89,468
Operating lease expense		218,841		210,791		659,879		524,780
Short-term lease rent expense		—		—		—		1,497
Total rent expense	$	218,841	$	210,791	$	659,879	$	526,277

The table below summarizes other information related to the Company’s operating leases:

	Nine Months Ended September 30,
	2020			2019
Operating cash flows for operating leases	$	665,095		$	550,024
Establishment of operating lease liabilities arising from obtaining right-of-use assets	$	21,078		$	2,038,193
Weighted-average remaining lease term – operating leases		1.9			2.4
Weighted-average discount rate – operating leases		9.6	%		9.6	%

As of September 30, 2020, remaining maturities of our operating leases, excluding short-term leases, are as follows:

2020	$	218,157
2021		340,970
2022		281,232
2023		70,848
Total		911,207
Less present value discount		(84,311	)
Operating lease liabilities, net	$	826,896

Financing Leases

The Company has a number of computer and copier equipment leases that are classified as financing leases. Incremental borrowing rates used to discount future lease payments in calculating lease liabilities were estimated by reference to information received by the Company from bankers regarding estimated current borrowing rates for collateralized loans with similar amount and duration as the leases. The Company does not have any material financing leases where it acts as a lessor.

The components of lease cost for financing leases were as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Financing leases
Amortization of right-of-use assets	$	10,035	$	10,128	$	34,033	$	36,908
Interest on lease liability		2,092		1,559		7,074		5,528
Total financing lease cost	$	12,127	$	11,687	$	41,107	$	42,436

The table below summarizes other information related to the Company’s financing leases:

	Nine Months Ended September 30,
	2020			2019
Weighted-average remaining lease term – financing leases		3.5			2.0
Weighted-average discount rate – financing leases		9.77	%		9.77	%

As of September 30, 2020, remaining maturities of our financing leases are as follows:

2020	$	10,445
2021		28,355
2022		20,716
2023		18,396
2024		16,080
Total		93,992
Less present value discount		(14,737	)
Financing lease liabilities, net	$	79,255

At September 30, 2020, the Company had financing lease liabilities net of discount of $79,255, of which $26,620 was included in other current liabilities and $52,635 was included in other non-current liabilities, and financing right-of-use assets of $75,563, which were included in property and equipment, net, in the accompanying condensed consolidated balance sheet.