Description The ESP-01S, building upon the ESP-01, features an optimized PCB antenna, representing a small step in upgrades but a giant leap in user experience. Product Basic Parameters: Operating Voltage: DC3.0-3.6V (3.3V recommended) SPI Flash: 1MB Onboard PCB Antenna Gain: 3DBi Product Dimension Diagram: Product Pin Definitions and Functions: Product Schematic Diagram: