The 0.91 inch is one of the most popular sizes of COG OLED for wearable displays. Winstar Graphic COG 128x32 OLED items no. WEO012832D is built-in with SSD1306 IC, it communicates via 4-wire serial SPI interface only. This controller's built-in voltage generation only need a single 3V power supply is needed. These COG 0.91 OLED modules are ultra thin, lightweight and low power consumption which is great for handheld instruments, meters, smart grid, wearable device, E-cigarette, MP3, IoT, etc.