Revenue is measured as consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. Amounts are billed upon completion of service or transfer of a product and are generally due within 30 days.

Revenues from contracts with customers are disaggregated into the following primary sources: services and products.

Service revenue is generated from time and material projects and consulting services. The Company generally establishes a master services agreement with each customer and provides associated services on a work order basis, generally by the hour for services performed. The majority of the Company’s contracts with customers are short-term in nature and are recognized as the services are performed, as the transfer of control to the customer and the Company’s right to payment corresponds directly to the services performed to date, at all times throughout completion of the contract.

Product revenue is generated from the resale of electrical and instrumentation equipment. Product contracts are established by agreeing on a sales price or transaction price for the related item. Payment terms for product contracts are generally thirty days from the receipt of the invoice. Product revenue is recognized upon delivery of the related item to the customer, at which point the customer controls the product and the Company has an unconditional right to payment.

All outstanding accounts receivable, net of allowance, on the consolidated balance sheet are typically due and collected within the next 12 months. Additionally, each month end the Company records unbilled revenue (a contract asset) based upon completed and partially completed performance obligations through month end providing the Company an unconditional right to payment for the services performed or products sold for the related period. The Company has no other material contract assets or liabilities and contract costs.

Taxes assessed by a governmental authority that are directly imposed on revenue-producing transactions between the Company and its customers, such as sales, use and value-added taxes, are excluded from revenue.

The table below presents revenue disaggregated by source, for the three and six months ended June 30, 2019 and 2018 (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Services		1,317		1,720		2,430		3,578
Products		638		355		741		373
	$	1,955	$	2,075	$	3,171	$	3,951