SR3100 is a special door section i meter. It is necessary to make full use of the advanced DSM2 in DX3R Spread spectrum protocol used by racing system. This means that it will any spread spectrum connection The has the fastest response, except for non-interference performance. And it gives you a bag, It is small enough to fit all these advantages in an easy 1/18 scale chassis. DSM2 spread spectrum Fastest response speed preset failsafe Type: channel of event receiver Band:2.4GHz Modulation:Digital Spread Modulation 2 Dimensions (WxLxH):.85x1.30x.48(in) 21.6x33.1x12.35(mm) Weight:21oz (6g) Voltage Range:3.5V-9.6V Colour:grey Material:plastic Package Contents: 1 x 1 x accessories 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.