We just got in stock a few of these new modules designed by the manufaturers of the Banana Pi. These are 4 channel I2C Bi-directional level shifters designed specifially to work with the Banana Pi computer board. Because the Banana Pi Board is a 5V device, and most modern sensors, displays, flash cards and modes are 3.3V-only, many makers find that they need to perform level shifting/conversion to protect the 3.3V device from 5V. If you need to down convert the bus voltage from 5V to 3.3V or 2.4V to 1.8V you would want to use one of these.
The module is made of NMOSFET, it makes the module have faster feedback and the low power consumption. There is a pull‐up resistor to solve the open‐drain output level not being stable.