10.	Commitments

Leases

The Company has entered into operating leases for facilities and equipment. These leases are non-cancellable and typically do not contain renewal options. Certain leases contain rent escalation clauses for which the Company recognizes the expense on a straight-line basis. Rent expense under the Company’s operating leases for the years ended December 31, 2017, 2016 and 2015 was approximately $3.1 million, $3.0 million and $3.0 million, respectively.

Future minimum lease payments under operating leases as of December 31, 2017 are as follows:

(U.S. Dollars, in thousands)
2018	$	3,017
2019		2,018
2020		1,240
2021		1,575
2022		1,600
Thereafter		12,156
Total	$	21,606

Inventory purchase commitments

The Company had inventory purchase commitments with third-party manufactures for $1.9 million and $1.2 million as of December 31, 2017, and 2016, respectively.