SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2021

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]

Estimated Useful Lives of Property, Plant and Equipment

Estimated useful lives of assets in the United States are as follows:

Computer and office equipment	3 to 5 years
Furniture and fixtures	5 years
Leasehold improvements	shorter of lease term or estimated useful life

ACM’s subsidiaries follow regulations for depreciation of fixed assets implemented under the PRC’s Enterprise Income Tax Law, which state that the minimum useful lives used for calculating depreciation for fixed assets are as follows:

Manufacturing equipment	for small to medium-sized equipment, 5 years; for large equipment, estimated by purchasing department at time of acceptance
Furniture and fixtures	5 years
Transportation equipment	4 to 5 years
Electronic equipment	3 to 5 years
Leasehold improvements	remaining lease term for improvements on leased fixed assets or, for large improvements, estimated useful life; not less than 3 years for non-fixed asset repairs

Warranty Obligations

The following table shows changes in the Company’s warranty obligations for the years ended December 31, 2021, 2020 and 2019 respectively.

	Year Ended December 31,
	2021			2020			2019
Balance at beginning of period		3,975			2,811			1,710
Additions		5,026			3,101			2,105
Utilized		(2,370	)		(1,937	)		(1,004	)
Balance at end of period	$	6,631		$	3,975		$	2,811

Basic and Diluted Net Income per Common Share

Basic and diluted net income per common share are calculated as follows:

	Year Ended December 31,
	2021		2020		2019
Numerator:
Net income	$	42,921	$	21,677	$	19,458
Less: Net income attributable to non-controlling interests and redeemable non-controlling interests		5,164		2,897		564
Net income available to common stockholders, basic	$	37,757	$	18,780	$	18,894
Less: Dilutive effect arising from share-based awards by ACM Shanghai		108		-		-
Net income available to common stockholders, diluted	$	37,649	$	18,780	$	18,894
Weighted average shares outstanding, basic		19,218,236		18,233,361		16,800,623
Effect of dilutive securities		2,567,336		2,950,108		2,334,874
Weighted average shares outstanding, diluted		21,785,572		21,183,469		19,135,497
Net income per common share:
Basic		1.96		1.03		1.12
Diluted	$	1.73	$	0.89	$	0.99

Concentration of Credit Risk

The Company is potentially subject to concentrations of credit risks in its accounts receivable. In the year ended December 31, 2021 and 2020, a total of two and three customers, respectively, individually accounted for greater than ten percent of the Company’s revenue:

	December 31,
	2021			2020
Customer A		28.1	%		36.9	%
Customer B		20.8	%		26.8	%
Customer C		*			12.1	%
Total		48.9	%		75.8	%

Translations of Foreign Exchange Rate

Translations of amounts from RMB and Korean Won into U.S. dollars were made at the following exchange rates for the respective dates and periods:

	At December 31,
	2021		2020		2019
Consolidated balance sheets:
RMB to $1.00		6.3757		6.5232		6.9784
KRW to $1.00		1,145.48		1,088.14		1,156.07

Consolidated statements of operations and comprehensive income:
RMB to $1.00	6.4515	6.8966	6.8966
KRW to $1.00	1,190.48	1,179.25	1,165.50