6. Other Intangible Assets

Other intangible assets consist of the following (U.S. dollars in thousands):

	Carrying Amount at December 31,
Indefinite life intangible assets:	2016		2017

Trademarks and trade names	$	24,599	$	24,599
Other indefinite lived intangibles		3,763		3,763
	$	28,362	$	28,362

	December 31, 2016				December 31, 2017
Finite life intangible assets:	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization		Weighted-average Amortization Period

Scanner technology	$	46,482	$	36,624	$	46,482	$	39,657	18 years
Developed technology		22,500		18,383		22,500		19,207	20 years
Distributor network		11,598		11,598		11,598		11,598	15 years
Trademarks		2,592		1,011		2,785		1,197	15 years
Other		46,219		26,584		57,550		29,971	8 years
	$	129,391	$	94,200	$	140,915	$	101,630	15 years

Amortization of finite-life intangible assets totaled $8.6 million, $8.4 million and $8.1 million for the years ended December 31, 2015, 2016 and 2017, respectively. In the year ended December 31, 2015, the Company wrote-off approximately $12.0 million of fully amortized intangible assets.

The estimated annual amortization expense for each of the five succeeding fiscal years are as follows (U.S. dollars in thousands):

Year Ending December 31,

	2018	$	8,978
	2019		8,876
	2020		4,898
	2021		4,148
	2022		5,201

Indefinite life intangible assets are not amortized, rather they are subject to annual impairment tests. Annual impairment tests were completed resulting in no impairment charges for any of the periods shown. Finite life intangibles are amortized over their useful lives unless circumstances occur that cause the Company to revise such lives or review such assets for impairment.