We have operating leases for office space, automobiles, and various other equipment in the United States and in certain international locations in which we do business. We also have other contracts, such as manufacturing agreements and service agreements, which we reviewed to determine if they contain any 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 June 30, 2019, our operating leases have remaining lease terms of one month to six years, some of which include options to extend the leases for up to three years, and some of which include 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 right of use liability. 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 $0.1 million and $0.3 million for the three and six months ended June 30, 2019, respectively, and is included in selling, general and administrative expenses on the Condensed Consolidated Statements of Income. For lease agreements entered into or reassessed after the adoption of Topic 842, we elected the practical expedient which allows us to not separate lease and non-lease components. None of our lease agreements contain any material residual value guarantees or material restrictive covenants.

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

		June 30,		January 1,
(In thousands)	Classification	2019		2019 ⁽¹⁾
Assets
Operating lease asset	Other assets	$	8,838	$	10,322
Total lease assets		$	8,838	$	10,322

Liabilities
Current operating lease liability	Accrued expenses	$	2,514	$	2,948
Non-current operating lease liability	Other non-current liabilities		6,349		7,374
Total lease liability		$	8,863	$	10,322

The components of lease expense included in the Condensed Consolidated Statements of Income for the three and six months ended June 30, 2019 are as follows:

(In thousands)	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
Selling, general and administrative expenses	$	349	$	698
Research and development expenses		430		884
Cost of sales		17		33
Total operating lease expense	$	796	$	1,615

As of June 30, 2019, operating lease liabilities included on the Condensed Consolidated Balance Sheet by future maturity are as follows:

(In thousands)	Amount
Remainder of 2019	$	1,583
2020		2,203
2021		2,047
2022		1,560
2023		1,173
Thereafter		756
Total lease payments		9,322
Less: Interest		(459	)
Present value of lease liabilities	$	8,863

Operating lease payments include $1.2 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, are 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 borrowing 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 is then determined based on a credit spread over LIBOR as well as the Bloomberg Curve Matrix for the U.S. Communications section.

	As of June 30, 2019
Weighted average remaining lease term (years)
Operating leases with USD functional currency		2.9
Operating leases with Euro functional currency		4.8
Weighted average discount rate
Operating leases with USD functional currency		4.61	%
Operating leases with Euro functional currency		1.85	%

(In thousands)	As of June 30, 2019
Cash paid for amounts included in the measurement of operating lease liabilities / assets
Cash used in operating activities related to operating leases	$	(797	)

Right-of-use assets obtained in exchange for lease obligations	$	10,396

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. 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 standalone sales 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. At June 30, 2019 and December 31, 2018, we had no allowance for credit losses for our net investment in sales-type leases. As of June 30, 2019 and December 31, 2018, the components of the net investment in sales-type leases were as follows:

	June 30,		December 31,
(In thousands)	2019		2018
Current minimum lease payments receivable (included in other receivables)	$	6,360	$	11,339
Non-current minimum lease payments receivable (included in other assets)		1,286		1,670
Total minimum lease payments receivable		7,646		13,009
Less: Current unearned revenue		495		631
Less: Non-current unearned revenue		269		473
Net investment in sales-type leases	$	6,882	$	11,905

The components of sales-type lease gross profit recognized at the lease commencement date and interest and dividend income, included in the Condensed Consolidated Statements of Income for the three and six months ended June 30, 2019, are as follows:

(In thousands)	Classification	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
Sales type leases	Sales - Network Solutions	$	109	$	1,621
Sales type leases	Cost of sales - Network Solutions		44		635
Sales type leases	Gross profit	$	65	$	986

Sales type leases	Interest and dividend income	$	99	$	186

As of June 30, 2019, future minimum lease payments to be received from sales-type leases are as follows:

(In thousands)	Amount
Remainder of 2019	$	5,705
2020		1,112
2021		525
2022		220
2023		81
Thereafter		3
Total	$	7,646