There are 4 fixing screw holes around the board, with a hole diameter of 3.1mm, making it easy to install and fix.The relay uses high-quality relay, single pole double throw. A common terminal, a normally open terminal, and a normally closed terminalLow level pull-in, high level release. The status indicator light is on when it is engaged and off when it is released.Relay maximum output: DC 30V/10A, AC 250V/10AWiring instructions:VCC: system power positive poleGND: negative pole of system power supplyIN1--IN8: relay control portColour:Photo ColorMaterial:plasticPackage Contents:1 x Relay moduleOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.