The revenues and expenses of the Group’s entities in the PRC are generally denominated in RMB and their assets and liabilities are denominated in RMB. The RMB is not freely convertible into foreign currencies. Remittances of foreign currencies into the PRC or remittances of RMB out of the PRC as well as exchange between RMB and foreign currencies require approval by foreign exchange administrative authorities and certain supporting documentation. The State Administration for Foreign Exchange, under the authority of the People’s Bank of China, controls the conversion of RMB into other currencies.

Financial instruments that potentially expose the Group to credit risk consist primarily of cash and cash equivalents, restricted cash, short-term investments, short-term deposits, accounts and notes receivable and amounts due from related parties. The Group places its cash and cash equivalents, restricted cash, short-term investments and short-term deposits with financial institutions with high credit ratings and quality. There has been no recent history of default in relation to these financial institutions and credit risk is immaterial.

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

Concentration risk of accounts and notes receivable from third parties are presented as below:

	As of December 31,
	2020				2021
	RMB				RMB
Company A		221,614	52	%		161,785	54	%
Company B		164,518	38	%		37,776	12	%

Concentration risk of accounts receivable from a related party are presented as below:

	As of December 31,
	2020				2021
	RMB				RMB
Xiaomi		609,094	100	%		320,939	100	%

Concentration risk of other receivables from related parties are presented as below:

	As of December 31,
	2020				2021
	RMB				RMB
Xiaomi		88,038	100	%		88,367	100	%

	Year ended December 31,
	2019				2020				2021
	RMB				RMB				RMB
Xiaomi		2,112,170	45	%		2,889,441	50	%		2,295,569	43	%

The revenue generated from Xiaomi included sale of both Xiaomi-branded and Viomi-branded products. Revenue from sale of Viomi-branded products amounted to RMB250,593, RMB326,114 and RMB274,452 for the years ended December 31, 2019, 2020 and 2021, respectively.