1).HP metal Extension for Transmitters. The extension positions your Transmitter further out from a 1st stage because the width of a Transmitter attached directly to the 1st stage means that it interferes with hoses attached to other ports.

So this is for when your Transmitter sits too tightly near on against the hoses that come out of the 1st stage reg.

2). HP 15cm (6") hose can also be used for the above reason too - but can also make it much safer for your transmitter - as mnay divers have had their Transmitter snap through the narrow metal thread that screws into the 1st stage when a buddy has grabbed the scuba rig by the top valve & 1st stage and puut pressure on the transmitter. The Transmitter is then dead; cannot be repaired.