Goodwill and Intangible Assets

The changes in the carrying amount of goodwill for the three months ended March 31, 2019 were as follows (in thousands):



	TASER		Software and Sensors		Total
Balance, beginning of period	$	1,338	$	23,643	$	24,981
Foreign currency translation adjustment	18		18		36
Balance, end of period	$	1,356	$	23,661	$	25,017

Intangible assets (other than goodwill) consisted of the following (in thousands):



		March 31, 2019							December 31, 2018
	Useful Life	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Amortizable (definite-lived) intangible assets:
Domain names	5-10 years	$	3,161	$	(808	)	$	2,353	$	3,161	$	(732	)	$	2,429
Issued patents	4-15 years	2,982		(1,158		)	1,824		2,940		(1,106		)	1,834
Issued trademarks	3-11 years	922		(490		)	432		1,053		(599		)	454
Customer relationships	4-8 years	3,717		(1,027		)	2,690		3,701		(880		)	2,821
Non-compete agreements	3-4 years	452		(375		)	77		540		(439		)	101
Developed technology	3-7 years	10,660		(4,889		)	5,771		13,404		(7,081		)	6,323
Re-acquired distribution rights	2 years	2,031		(2,031		)	—		1,928		(1,813		)	115
Total amortizable		23,925		(10,778		)	13,147		26,727		(12,650		)	14,077
Not amortizable (indefinite-lived) intangible assets:
TASER trademark		900					900		900					900
Patents and trademarks pending		1,020					1,020		958					958
Total not amortizable		1,920					1,920		1,858					1,858
Total intangible assets		$	25,845	$	(10,778	)	$	15,067	$	28,585	$	(12,650	)	$	15,935

Amortization expense of intangible assets for the three months ended March 31, 2019 and 2018 was $1.0 million and $1.4 million, respectively. Estimated amortization for intangible assets with definite lives for the remaining nine months of 2019, the next five years ended December 31, and thereafter, is as follows (in thousands):



2019 Remaining	$	2,501
2020	3,293
2021	2,846
2022	1,244
2023	946
2024	862
Thereafter	1,455
Total	$	13,147