We have various noncancellable lease agreements for office and warehouse space, as well as office equipment, with original remaining lease terms of two years to nine years, some of which include an option to extend the lease term for up to five years. Because the Company is not reasonably certain to exercise these renewal options, the options are not considered in determining the lease term, and associated potential option payments are excluded from lease payments. The Company’s leases generally do not include termination options for either party to the lease or restrictive financial or other covenants.

Weighted-average remaining lease term (in years) and discount rate related to operating leases were as follows:

As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the date of adoption to determine the present value of lease payments.

Maturities of lease liabilities under noncancellable operating leases as of March 31, 2019 were as follows:

	March 31 ,2019

2019 (a)	$	1,017,527
2020		1,521,149
2021		1,724,052
2022		1,727,538
2023		1,773,769
2024 and beyond		4,287,729
Total lease payments		12,051,764
Less: Imputed interest		(2,387,800	)
Present value of lease liabilities	$	9,663,964

As of December 31, 2018 minimum lease payments under noncancellable operating leases by period were expected to be:

	December 31,
	2018

2019	$	1,475,761
2020		1,626,179
2021		1,671,003
2022		1,664,510
2023		1,700,539
2024 and thereafter		4,246,015
	$	12,384,007

A summary of rent expense for the years ended December 31, 2018 and 2017 was as follows:

		2018				2017
Rent expense		$	515,565			$	480,349

Supplemental cash flow information and non-cash activity relating to operating leases are as follows:



	For the Three Months Ended March 31, 2019
Operating cash flow information:
Cash paid for amounts included in the measurement of lease liabilities	$	246,735