Electric speed sensor (known as PAS, wheel mounted sensor). It is a high-tech component designed for electric with ergonomics. It has superiority to match well with all electric s available in the market. It employs the dual-magnetic loop - Hall elastic angle difference to detect the dynamic , which is converted to DC signal and sent to the controller. 1:1 power assist. Make cycling easier and funnier. suitable for most bike: This sensor has superiority to match well with all electric bicycles available in the market.suitable for 12-72V voltage and most electric bicycles, mountain bikes, road bikes and snowmobiles. Colour:Black Material:magnetic steel+Plastic Type:12 magnetic Package Contents: 3x Electric bicycle pulse assist sensor Only 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.