Revenues are recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. Our product sales and shipping revenues are reported net of promotional discounts, returns allowances, contractual rebates, and consideration payable to our customers. We estimate the revenue impact of retail sales incentive programs based on the planned duration of the program and historical experience. If the amount of sales incentives is reasonably estimable, the impact of such incentives is recorded at the later of the

time the customer is notified of the sales incentive or the time of the sale. We estimate our liability for product returns based on historical experience, and record the expected customer refund liability as a reduction of revenue, and the expected inventory right of recovery, net of estimated scrap, as a reduction of cost of sales. If actual return costs differ from previous estimates, the amount of the liability and corresponding revenue are adjusted in the period in which such costs occur.

We provide standard assurance-type warranties on our products which cover defective materials or nonconforming products, and is included with each product at no additional charge. In addition, we offer service-type/extended warranties for an additional fee to our Direct channel customers and Retail specialty and commercial customers. These warranty contracts provide coverage on labor and parts beyond the standard assurance warranty period.

For our product sales, services, and freight and delivery fees, we are the principal in the contract and recognize revenue at a point in time. For our Direct channel extended warranty contracts, we are the agent and recognize revenue on a net basis because our performance obligation is to facilitate the arrangement between our customers and the third-party performance obligor.

For customer contracts that include multiple performance obligations, we allocate revenue to each performance obligation based on its relative standalone selling price. We generally determine standalone selling price based on prices charged to customers or using expected cost plus margin.

Our revenues from contracts with customers disaggregated by revenue source, excluding sales-based taxes, were as follows (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Product sales	$	56,326	$	71,470	$	136,458	$	181,220
Extended warranties and services	1,168		1,737		3,637		5,219
Other⁽¹⁾	1,510		2,291		3,309		3,872
Net sales	$	59,004	$	75,498	$	143,404	$	190,311



	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
United States	$	48,897	$	65,498	$	119,085	$	169,079
Canada	3,557		3,283		11,486		9,066
All other	6,550		6,717		12,833		12,166
Net sales	$	59,004	$	75,498	$	143,404	$	190,311

As of June 30, 2019, estimated revenue expected to be recognized in the future totaled $1.8 million, primarily related to customer order backlog, which includes firm orders for future shipment to our Retail customers, as well as unfulfilled consumer orders within the Direct channel. Retail orders of $1.4 million and Direct orders of $0.4 million comprise our backlog as of June 30, 2019. The estimated future revenues are net of contractual rebates and consideration payable for applicable Retail customers, and net of current promotional programs and sales discounts for our Direct customers.

The following table provides information about our liabilities from contracts with customers, primarily customer deposits and deferred revenue, all of which are short-term in nature. The revenue recognized from contract liabilities and the remaining balances are presented in accrued liabilities and are shown below (in thousands):



	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Balance, beginning of period	$	479		$	693		$	816		$	1,084
Cash additions	351			304			512			993
Revenue recognition	(268		)	(249		)	(766		)	(1,329		)
Balance, end of period	$	562		$	748		$	562		$	748

We apply the practical expedient as per ASC 606-10-50-14 and do not disclose information related to remaining performance obligations due to their original expected durations are one year or less.

We expense sales commissions when incurred because the amortization period would have been less than one year. These costs are recorded in selling and marketing expense.