The Garmin Descent T1 Cap and O-Ring Kit replaces that of the Garmin Descent T1 Transmitter. It comes with a top cap, both internal and external O-Ring, and also the necessary lubricant for installation.

Having the Garmin Descent T1 Cap and O-Ring Kit as a spare well can be useful in emergency situations such as when divers accidentally damage the cap of the wireless diving transmitter during a battery change.