Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and accounts receivable. The Company places its cash with financial institutions with high credit ratings and quality.

The Company conducts credit evaluations of customers, and generally does not require collateral or other security from its customers. The Company establishes an allowance for doubtful accounts primarily based upon the age of the receivables and factors surrounding the credit risk of specific customers.

Accounts receivable are unsecured and are derived from revenue earned through customers. The risk with respect to accounts receivable is mitigated by credit evaluations performed on them.

The Company believes it is not exposed to significant credit risk on cash and accounts receivable.

As of December 31, 2022 and 2023, accounts receivable were nil and US$2,997, respectively.


	As of December 31,
	2022	2023
Customer A	—	97	%


	For the Years Ended December 31,
	2021		2022		2023
Customer B	*		33	%	*
Customer C	18	%	22	%	*
Customer D	*		16	%	*
Customer E	*		*		14	%

For the year ended December 31, 2021, the Company’s purchases of its integrated circuits mainly from one supplier.

For the year ended December 31, 2022, the Company’s purchases substantially all its integrated circuits from three suppliers.

For the year ended December 31, 2023, the Company’s purchases substantially all its integrated circuits from two suppliers.

Although only a limited number of manufacturers for such integrated circuits are available, management believes that they could change their suppliers within these manufacturers which provided integrated circuits on comparable terms. A change in suppliers, however, could cause a delay in manufacturing and a possible loss of sales, which would affect operating results adversely.