The ESP-01 Breakout Adapter for ESP8266 serial to Wi-Fi transceiver module. Since the ESP-01 pinout is not breadboard friendly and unlabeled, this makes it inconvenient for rapid prototyping.
The 2SK2837, 2SK-2837, K2837, 2837 is a 500V 20A N Channel Silicon Field Effect Transistor Or MOFET TO-3PN-3 Package. Chopper Regulator, DC−DC Converter and Motor Drive.