4. REVENUE

Substantially all of our revenue is generated from sales of towing equipment. As such, disaggregation of revenue by product line would not provide useful information because all product lines have substantially similar characteristics. However, revenue streams are tracked by the geographic location of customers. This disaggregated information is presented in the table below.


	For the Three Months Ended				For the Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Net Sales:
North America	$	191,753	$	143,137	$	355,646	$	274,781
Foreign		30,593		33,751		63,913		61,267
	$	222,346	$	176,888	$	419,559	$	336,048

Revenue is recognized when obligations under the terms of a contract with a customer are satisfied. Except for certain extended service contracts on a small percentage of units sold, the Company’s performance obligations are satisfied, and sales revenue is recognized when products are shipped from the Company’s facilities. From time to time, revenue is recognized under a bill and hold arrangement. Recognition of revenue on bill and hold arrangements occurs when control transfers to the customer. The bill and hold arrangement must be substantive, and the product must be separately identified as belonging to the customer, ready for physical transfer, and unavailable to be used or directed to another customer.

Revenue is measured as the amount of consideration expected to be received in exchange for the transfer of products. Sales and other taxes collected concurrent with revenue-producing activities are excluded from revenue. Warranty related costs are recognized as an expense at the time products are sold. Depending on the terms of the arrangement, for certain contracts the Company may defer the recognition of a portion of the consideration received because a future obligation has not yet been satisfied, such as an extended service contract. An observable price is used to determine the stand-alone selling price for separate performance obligations or a cost plus margin approach is utilized when one is not available.

Contract assets primarily relate to the Company’s rights to consideration for work completed but not billed at the reporting date. The contract assets are transferred to receivables when the rights become unconditional. Contract liabilities primarily relate to performance obligations to be satisfied in the future. As of June 30, 2019, and December 31, 2018, contract liability balances related to extended service contracts were $700 and $331, respectively, and are included in accrued liabilities on the consolidated balance sheets. No revenue related to contract liability balances was recognized during the three and six months ended June 30, 2019 and 2018. The Company did not have any contract assets at June 30, 2019 or December 31, 2018. Terms on accounts receivable vary and are based on specific terms agreed upon with each customer. Impairment losses on accounts receivable were de minimis during the three and six months ended June 30, 2019 and 2018.

Trade accounts receivable are generally diversified due to the number of entities comprising the Company’s customer base and their dispersion across many geographic regions and by frequent monitoring of the creditworthiness of the customers to whom the credit is granted in the normal course of business. At December 31, 2018 the Company had one customer with a trade account receivable balance greater than 10% of total accounts receivable, which account subsequently decreased to less than 10% of the total accounts receivable balance at June 30, 2019.