This grommet provides strain relief for the Di2 cable as it exits the chainstay where the cable cup normally is on a Cannondale CAAD12. This is needed for CAAD12 Di2 installations to protect the rear derailleur wire. This item contains only the rear chainstay grommet. We also sell complete kits to plug all holes for Di2 and eTAP conversions. The new grommets are made from a softer, and more durable material.