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 March 31, 2019
	Mobile Solutions		Power Solutions		Life Sciences		Intersegment Sales Eliminations			Total
United States	$	44,457	$	41,115	$	68,343	$	(484	)	$	153,431
China	9,153		1,838		1,692		—			12,683
Mexico	5,378		2,709		127		—			8,214
Brazil	8,382		69		—		—			8,451
Germany	1,406		16		8,885		—			10,307
Switzerland	1,359		16		3,265		—			4,640
Poland	1,913		4		6		—			1,923
Italy	1,856		63		421		—			2,340
Czech Republic	1,509		188		—		—			1,697
France	44		—		1,225		—			1,269
Africa	—		1,156		—		—			1,156
Other	2,618		2,483		2,044		—			7,145
Total net sales	$	78,075	$	49,657	$	86,008	$	(484	)	$	213,256



	Three Months Ended March 31, 2018
	Mobile Solutions		Power Solutions		Life Sciences		Intersegment Sales Eliminations			Total
United States	$	49,655	$	40,128	$	30,553	$	(528	)	$	119,808
China	11,581		1,485		126		—			13,192
Mexico	7,236		3,197		172		—			10,605
Brazil	9,885		50		—		—			9,935
Poland	2,052		14		—		—			2,066
Czech Republic	1,810		—		—		—			1,810
Italy	1,577		98		—		—			1,675
Germany	1,534		7		1		—			1,542
Switzerland	1,406		—		—		—			1,406
Netherlands	—		974		—		—			974
Other	3,058		2,729		348		—			6,135
Total net sales	$	89,794	$	48,682	$	31,200	$	(528	)	$	169,148

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 March 31, 2019	$	2,890

Revenue recognized during the three months ended March 31, 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 $0.6 million.

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 March 31, 2019, unless our contracts meet one of the practical expedients. Our contracts met the following practical expedient provided by the guidance:


•	The performance obligation is part of a contract that has an original expected duration of one year or less.

Sales Concentration

During the three months ended March 31, 2019, we recognized sales from a single customer of $23.3 million, or 10.9% 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 months ended March 31, 2018.