Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows From Operating Activities
Net income	$ 3,697	$ 3,042
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	154	102
Stock-based compensation	733	320
Write-off of long lived assets	9
Deferred income taxes	(135)	(19)
Changes in operating assets and liabilities:
Accounts receivable	19	(157)
Inventory	(245)	(1,418)
Prepaid expenses and other current assets	(214)	100
Other assets	(7)	(10)
Accounts payable	422	(1,026)
Accrued expenses	324	214
Customer deposits	(645)	(1,154)
Other liabilities	41	53
Net cash provided by operating activities	4,153	47
Cash Flows From Investing Activities
Purchase of property and equipment	(145)	(313)
Net cash used in investing activities	(145)	(313)
Cash Flows From Financing Activities
Proceeds from initial public offering, net of underwriter commission	8,139
Net proceeds from exercise of stock options	26	112
Payments of deferred offering costs	(1,355)	(735)
Net cash provided by (used in) financing activities	6,810	(623)
Net increase in cash and cash equivalents	10,818	(889)
Cash and cash equivalents at beginning of period	10,006	9,463
Cash and cash equivalents at end of period	20,824	8,574
Supplemental Disclosure of Cash Flow Information
Cash paid for income taxes	1,834	1,230
Supplemental Disclosure of Noncash Investing and Financing Information
Conversion of preferred stock to common stock upon initial public offering	8,792
Unpaid deferred offering costs	741	144
Vesting of early exercised options	$ 79	58
Property and equipment purchased but not yet paid		$ 2