We have operating leases for office space, automobiles and various other equipment in the U.S. and in certain international locations. We also reviewed other contracts, such as manufacturing agreements and service agreements, for potential embedded leases. We specifically reviewed these other contracts 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, 2019, our operating leases had remaining lease terms of one month to six years, some of which included options to extend the leases for up to nine 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. Leases with an initial term of 12 months or less were 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 $0.4 million for the twelve months ended December 31, 2019, and is included in cost of sales, selling, general and administrative expenses and research and development expenses in the Consolidated Statements of 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 $0.9 million for the twelve months ended December 31, 2019. For lease agreements entered into or reassessed after the adoption of Topic 842, we elected to not separate lease and nonlease components. Our lease agreements do not contain any material residual value guarantees or material restrictive covenants.

Supplemental balance sheet information related to operating leases is as follows:

		December 31,		January 1,
(In thousands)	Classification	2019		2019 ⁽¹⁾
Assets
Right of use lease assets	Other assets	$	8,452	$	10,322
Total lease asset		$	8,452	$	10,322

Liabilities
Current lease liability	Accrued expenses	$	2,676	$	2,948
Non-current lease liability	Other non-current liabilities		5,818		7,374
Total lease liability		$	8,494	$	10,322

The components of lease expense included in the Consolidated Statements of Income for the twelve months ended December 31, 2019 were as follows:

	For the Year Ended December 31,
(In thousands)	2019
Research and development expenses	$	2,417
Selling, general and administrative expenses		1,400
Cost of sales		64
Total operating lease expense	$	3,881

As of December 31, 2019, operating lease liabilities included on the Consolidated Balance Sheet by future maturity were as follows:

(In thousands)	Amount
2020	$	2,856
2021		2,412
2022		1,705
2023		1,160
2024		482
Thereafter		264
Total lease payments		8,879
Less: Interest		(385	)
Present value of lease liabilities	$	8,494

Future operating lease payments include $0.7 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.

As of December 31, 2018, future minimum rental payments under non-cancelable operating leases, including renewals determined to be reasonably assured as of December 31, 2018, with original maturities of greater than 12 months, were as follows:

(In thousands)	Amount (1)
2019	$	3,873
2020		3,580
2021		2,771
2022		2,053
2023		1,317
Thereafter		762
Total	$	14,356

Our leases do not provide an implicit rate and therefore we use an incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We used the incremental borrowing rate on January 1, 2019, for operating leases that commenced on or prior to that date. The incremental borrowing rate was 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 was 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, 2019:

	As of December 31,
	2019
Weighted average remaining lease term (years)
Operating leases with USD functional currency		2.6
Operating leases with Euro functional currency		4.4
Weighted average discount rate
Operating leases with USD functional currency		4.02	%
Operating leases with Euro functional currency		1.84	%

	As of December 31,
(In thousands)	2019
Cash paid for amounts included in the measurement of operating lease assets / liabilities
Cash used in operating activities related to operating leases	$	3,439
Right-of-use assets obtained in exchange for lease obligations	$	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 nonlease 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, 2019 and 2018, we did not have an allowance for credit losses for our net investment in sales-type leases. As of December 31, 2019 and 2018, the components of the net investment in sales-type leases were as follows:

	December 31,		December 31,
(In thousands)	2019		2018
Current minimum lease payments receivable⁽¹⁾	$	1,201	$	11,339
Non-current minimum lease payments receivable⁽²⁾		889		1,670
Total minimum lease payments receivable		2,090		13,009
Less: Current unearned revenue⁽¹⁾		365		631
Less: Non-current unearned revenue⁽²⁾		163		473
Net investment in sales-type leases	$	1,562	$	11,905

The components of sales-type lease gross profit recognized at the lease commencement date and interest and dividend income, included in the Consolidated Statements of Income for the twelve months ended December 31, 2019 were as follows:

(In thousands)	For the Year Ended December 31, 2019
Sales - Network Solutions	$	1,723
Cost of sales - Network Solutions		675
Gross profit	$	1,048

Interest and dividend income	$	357

As of December 31, 2019 future minimum lease payments to be received from sales-type leases were as follows:

(In thousands)	Amount
2020	$	1,201
2021		565
2022		232
2023		86
2024		6
Total	$	2,090