SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration risks (Details)	3 Months Ended
	Mar. 31, 2026 USD ($) customer	Mar. 31, 2025 USD ($) customer
Concentration risks
Aggregate dollar amount of net sales	$ 7,177,397	$ 8,295,173
Other products
Concentration risks
Aggregate dollar amount of net sales	$ 6,987	$ 7,684
Net Sales | Customer Concentration Risk
Concentration risks
Number of significant customers | customer	2	3
Net Sales | Customer Concentration Risk | Significant customers
Concentration risks
Aggregate dollar amount of net sales	$ 3,400,000	$ 4,900,000
Concentration risk, percentage	47.10%	58.60%
Cost of Sales, Manufacturing | Supplier Concentration Risk | China
Concentration risks
Concentration risk, percentage	61.00%	62.70%