Summary of significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2016

Summary of significant accounting policies [Abstract]

Allowance for doubtful accounts

The following table summarizes the activity recorded in the valuation account for accounts receivable:

	Year ended December 31,
(In thousands)	2016		2015			2014
Balance, beginning of period	$	50	$	100		$	63
Additions charged to costs and expenses		-		7			37
Write-offs		-		(57	)		-
Balance, end of period	$	50	$	50		$	100

Concentration of risk

Accounts receivable from customers representing 10% or more of total accounts receivable were as follows:

	December 31,
	2016			2015
IGT		34	%		17	%
Suzo-Happ		18	%		10	%
CMC Daymark		8	%		13	%
Panasonic		3	%		11	%

Sales to customers representing 10% or more of total net sales were as follows:

	Year ended December 31,
	2016			2015			2014
IGT		26	%		29	%		19	%
Suzo-Happ		15	%		14	%		7	%
Eurocoin		-	%		-	%		11	%

Product warranty liability

The following table summarizes the activity recorded in the accrued product warranty liability:

	Year ended December 31,
(In thousands)	2016			2015			2014
Balance, beginning of period	$	277		$	287		$	366
Warranties issued		254			267			183
Warranty settlements		(264	)		(277	)		(262	)
Balance, end of period	$	267		$	277		$	287