Amazon.com: Tolako 5V 4 Channel Solid State Relay 4CH SSR Module for Arduino Uno Duemilanove MEGA2560 MEGA1280 ARM DSP PIC (4CH) : Industrial & Scientific
Amazon.com: ELEGOO 4 Channel DC 5V Relay Module with Optocoupler Compatible with Arduino UNO R3 MEGA 2560 DSP ARM PIC AVR STM32 Raspberry Pi : Electronics
NOYITO 4-Channel Relay Module DC 5V 12V 24V Self-Locking Triggering Interlocking High Low Level Trigger for PLC Industrial Control (12V): Amazon.com: Industrial & Scientific
4 Channel 5V Relay Module - Wiki
5V Four-Channel Relay Module - Pin Diagram, Specifications, Applications, Working
ELEGOO Relay Module with Optocoupler for Arduino UNO R3 MEGA 2560 1280 DSP ARM PIC AVR STM32 Raspberry Pi – ELEGOO Official
SOLVED] Wiring of a dual channel relay: HL-52S question - Project Guidance - Arduino Forum