E-tube Di2 D-FLY data transmission wireless unit,Allows information to be sent wirelessly via ANT+ private network to compatible cycle computers,Information can be displayed about gear position and Di2 battery level,Clean integration and installation with E-tube system,Internal chip enables system wireless functionality of Bluetooth components,Plug tool required for inserting and removing E-tube Di2 wires,Approximate size 38 x 25 x 12.5 mm,To be used in conjunction with BT-DN110 or SM-BTR1,Average weight 5 grams.