wiki:A relay is an electrically operated switch, which has a control system and the controlled system, usually used in automatic control circuit.
Gravity : relay module, Max 16A @ 250V AC, Max 16A @ 24V DC, Power : 5V, DFR0251
16A Relay module Gravity, digital
Gravity: Digital 5A Relay Module for Arduino - DFRobot
DFRobot Gravity - relay 1 channel - 277VAC / 16A Botland - Robotic Shop
Gravity: Easy Switch Module - DFRobot
Buy DFRobot 4x Relay - Shield for Arduino v2.1 Botland - Robotic Shop
Gravity: Digital 5A Relay Module for Arduino - DFRobot
Gravity: Magnetic Latching Relay Module for ESP32 / Arduino - DFRobot
1 Channel 5V Relay Module
Gravity: 16A Relay Module For Arduino - DFRobot
Buy Gravity - relay module - with DC-USB adapters Botland - Robotic Shop