
No documentation, but the GPIO to relay mapping is on the circuit board under the yellow jumpers. This is misleading as they are marked as P5, P6, P13, P16, P19, P20, P21, P26 but they are actually GPIO, GPIO5, GPIO6, GPIO13 etc numbers not PI pin numbers.

π MCIGICM 2 Channel DC 5V Relay Module: Optocoupler Low Level Trigger Expansion Board for Arduino UNO R3, DSP, ARM, PIC, AVR, STM32, Raspberry Pi
11 Review

Vilros Raspberry Pi 4 4GB Complete Starter Kit - Black Fan-Cooled Aluminum Case for Heavy-Duty Performance
12 Review

GeeekPi Raspberry Pi Cluster Case with Cooling Fan and Heatsink for Pi 4 Model B, 3 Model B+ & 3/2 Model B
11 Review

π Ultimate BBC Micro bit Sensor Starter Kit: Keyestudio 37-in-1 Box with Tutorial, Compatible with V1.5 & V2, Gift for Kids and Adults (Microbit Board Not Included)
11 Review

36-Pack Black Rubber PC CPU/Case Fan Screws/Rivets Set for Computer
11 Review

uxcell 3.5" HDD Screw Black 200pcs for Computer PC Case - Flat Phillips Head - 6#-32 - Hard Drive Fasteners
10 Review

Glarks 660 Pieces Phillips Assortment Motherboard
10 Review

MacBook Retina 13-inch (A1425, A1502) and π© 15-inch (A1398) Bottom Case Screw Set with Pentalobe Screwdriver
11 Review