Revenue from Contracts with Customers

Revenue is recognized when control of the good or service is transferred to the customer either at a point in time or, in limited circumstances, as our services are rendered over time. Revenue is measured as the amount of consideration we expect to receive in exchange for transferring goods or services. Sales, value add, and other taxes we collect concurrent with revenue-producing activities are excluded from revenue. Incidental items that are immaterial in the context of the contract are recognized as expense.

The following tables summarize sales to external customers by major source.



	Three Months Ended June 30, 2019
	Mobile Solutions		Power Solutions		Life Sciences		Intersegment Sales Eliminations			Total
United States	$	44,512	$	40,580	$	74,229	$	(503	)	$	158,818
China	9,318		1,598		1,873		—			12,789
Germany	1,316		21		8,447		—			9,784
Brazil	9,636		80		—		—			9,716
Mexico	5,066		4,235		117		—			9,418
Switzerland	1,153		25		3,509		—			4,687
Other	8,443		4,854		3,157		—			16,454
Total net sales	$	79,444	$	51,393	$	91,332	$	(503	)	$	221,666



	Three Months Ended June 30, 2018
	Mobile Solutions		Power Solutions		Life Sciences		Intersegment Sales Eliminations			Total
United States	$	48,142	$	41,924	$	48,441	$	(703	)	$	137,804
China	11,581		959		1,312		—			13,852
Mexico	7,236		3,348		167		—			10,751
Brazil	9,637		—		29		—			9,666
Germany	1,551		—		3,816		—			5,367
Switzerland	1,294		29		1,720		—			3,043
Other	8,638		3,560		3,668		—			15,866
Total net sales	$	88,079	$	49,820	$	59,153	$	(703	)	$	196,349



	Six Months Ended June 30, 2019
	Mobile Solutions		Power Solutions		Life Sciences		Intersegment Sales Eliminations			Total
United States	$	88,969	$	81,695	$	142,572	$	(987	)	$	312,249
China	18,471		3,436		3,565		—			25,472
Germany	2,722		37		17,332		—			20,091
Brazil	18,018		149		—		—			18,167
Mexico	10,444		6,944		244		—			17,632
Switzerland	2,512		41		6,775		—			9,328
Other	16,383		8,748		6,852		—			31,983
Total net sales	$	157,519	$	101,050	$	177,340	$	(987	)	$	434,922



	Six Months Ended June 30, 2018
	Mobile Solutions		Power Solutions		Life Sciences		Intersegment Sales Eliminations			Total
United States	$	97,797	$	82,052	$	78,994	$	(1,231	)	$	257,612
China	23,162		2,444		1,438		—			27,044
Mexico	14,472		6,545		339		—			21,356
Brazil	19,522		50		29		—			19,601
Germany	3,085		7		3,817		—			6,909
Switzerland	2,700		29		1,720		—			4,449
Poland	3,971		18		1		—			3,990
Other	13,164		7,357		4,015		—			24,536
Total net sales	$	177,873	$	98,502	$	90,353	$	(1,231	)	$	365,497

Deferred Revenue

The following table provides information about contract liabilities from contracts with customers.



	Deferred Revenue
Balance at January 1, 2019	$	2,974
Balance at June 30, 2019	$	2,953

Revenue recognized during the three and six months ended June 30, 2019, from amounts included in deferred revenue at the beginning of the period for performance obligations satisfied or partially satisfied during the period, was approximately $0.9 million and $1.6 million, respectively.

Transaction Price Allocated to Future Performance Obligations

We are required to disclose the aggregate amount of transaction price that is allocated to performance obligations that have not yet been satisfied as of June 30, 2019, unless our contracts meet one of the practical expedients. Our contracts met the practical expedient for a performance obligation that is part of a contract that has an original expected duration of one year or less.

Sales Concentration

During the three months ended June 30, 2019, we recognized sales from a single customer of $23.0 million, or 10.4% of consolidated net sales. During the six months ended June 30, 2019, we recognized sales from a single customer of $45.1 million, or 10.4% of consolidated net sales. Revenues from this customer are in our Life Sciences and Power Solutions groups. No customers represented more than 10% of our net sales during the three and six months ended June 30, 2018.