We have operating leases for office space, automobiles and various other equipment in the U.S. and in certain international locations. Other contracts, such as manufacturing agreements and service agreements, are reviewed to determine if they contain potential embedded leases. These other contracts are specifically reviewed to determine whether we have the right to substantially all of the economic benefit from the use of any specified assets or the right to direct the use of any specified assets, either of which would indicate the existence of a lease.

As of December 31, 2021, our operating leases had remaining lease terms of one month to forty four months, some of which included options to extend the leases for up to two years, and some of which included options to terminate the leases within three months. For those leases that are reasonably assured to be renewed, we have included the option to extend as part of our right of use asset and lease liability. Supplemental balance sheet information related to operating leases is as follows:


		December 31,		December 31,
(In thousands)	Classification	2021		2020
Assets
Operating lease assets	Other non-current assets	$	4,922	$	5,309
Total lease asset		$	4,922	$	5,309

Liabilities
Current operating lease liability	Accrued expenses and other liabilities	$	1,730	$	1,806
Non-current operating lease liability	Other non-current liabilities		3,269		3,574
Total lease liability		$	4,999	$	5,380

Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term. Lease expense related to these short-term leases was less than $0.1 million for the twelve months ended December 31, 2021 and 2020 and was $0.4 million of the twelve months ended December 31, 2019, and is included in cost of revenue, selling, general and administrative expenses and research and development expenses in the Consolidated Statements of (Loss) Income. Lease expense related to variable lease payments that do not depend on an index or rate, such as real estate taxes and insurance reimbursements, was $0.5 million, $0.7 million and $0.9 million for the twelve months ended December 31, 2021, 2020 and 2019, respectively. For lease agreements entered into or reassessed after the adoption of Topic 842, we elected to not separate lease and non-lease components. Our lease agreements do not contain any material residual value guarantees or material restrictive covenants.

The components of lease expense included in the Consolidated Statements of (Loss) Income were as follows:


	For the Year Ended December 31,
(In thousands)	2021		2020		2019
Cost of revenue	$	51	$	113	$	64
Selling, general and administrative expenses		883		1,311		1,400
Research and development expenses		1,071		1,121		2,417
Total operating lease expense	$	2,005	$	2,545	$	3,881

As of December 31, 2021, operating lease liabilities included on the Consolidated Balance Sheet by future maturity were as follows:


(In thousands)	Amount
2022		1,767
2023		1,419
2024		1,188
2025		710
Thereafter		—
Total lease payments		5,084
Less: Interest		(85	)
Present value of lease liabilities	$	4,999

Future operating lease payments include $1.6 million related to options to extend lease terms that are reasonably certain of being exercised. There are no legally binding leases that have not yet commenced.

An incremental borrowing rate is used based on information available at the commencement date in determining the present value of lease payments. The incremental borrowing rate is determined on a portfolio basis by grouping leases with similar terms as well as grouping leases based on a U.S. dollar or Euro functional currency. The actual rate is then determined based on a credit spread over LIBOR as well as the Bloomberg Curve Matrix for the U.S. Communications section. The following table provides information about our weighted average lease terms and weighted average discount rates:


	As of December 31,
Weighted average remaining lease term (years)	2021			2020
Operating leases with USD functional currency		1.8			2.4
Operating leases with Euro functional currency		3.5			3.6
Weighted average discount rate
Operating leases with USD functional currency		3.49	%		4.47	%
Operating leases with Euro functional currency		1.22	%		1.37	%

Supplemental cash flow information related to operating leases is as follows:


	For the year ended December 31,
(In thousands)	2021		2020		2019
Cash used in operating activities related to operating leases	$	1,892	$	2,632	$	3,439
Right-of-use assets obtained in exchange for operating lease obligations	$	1,875	$	324	$	11,615

We are the lessor in sales-type lease arrangements for network equipment, which have initial terms of up to five years. Our sales-type lease arrangements contain either a provision whereby the network equipment reverts back to us upon the expiration of the lease or a provision that allows the lessee to purchase the network equipment at a bargain purchase amount at the end of the lease. In addition, our sales-type lease arrangements do not contain any residual value guarantees or material restrictive covenants. The allocation of the consideration between lease and non-lease components is determined by stand-alone selling price by component. The net investment in sales-type leases consists of lease receivables less unearned income. Collectability of sales-type leases is evaluated periodically at an individual customer level. The Company has elected to exclude taxes related to sales-type leases from revenue and the associated expense of such taxes. As of December 31, 2021 and 2020, we did not have an allowance for credit losses for our net investment in sales-type leases. As of December 31, 2021 and 2020, the components of the net investment in sales-type leases were as follows:


	As of December 31,
(In thousands)	2021		2020
Current minimum lease payments receivable(1)	$	92	$	702
Non-current minimum lease payments receivable(2)		4		347
Total minimum lease payments receivable		96		1,049
Less: Current unearned revenue(1)		70		218
Less: Non-current unearned revenue(2)		1		50
Net investment in sales-type leases	$	25	$	781

(1)

Included in other receivables on the Consolidated Balance Sheets.

(2)

Included in other non-current assets on the Consolidated Balance Sheets.

Components of gross profit related to sales-type lease recognized at the lease commencement date and interest and dividend income, included in the Consolidated Statements of (Loss) Income for the twelve months ended December 31, 2021 and 2020 were as follows:


	For the year ended December 31,
(In thousands)	2021		2020		2019
Revenue - Network Solutions	$	22	$	78	$	1,723
Cost of revenue - Network Solutions		5		32		675
Gross profit	$	17	$	46	$	1,048

Interest and dividend income	$	27	$	42	$	357

As of December 31, 2021 future minimum lease payments to be received from sales-type leases were as follows:


(In thousands)	Amount
2022	$	92
2023		4
2024		—
2025		—
2026		—
Thereafter		—
Total	$	96