5pcs 4 Channel Bi-directional Iic I2c Logic Level Converter Module 5v 3.3v Dc Module For Arduino With Pins High Low Voltage - Voltage Regulators/stabilizers - AliExpress
4-channel I2C-safe Bi-directional Logic Level Converter [BSS138] : ID 757 : $3.95 : Adafruit Industries, Unique & fun DIY electronics and kits