Dr Tuba Replacement Strut Bladder
The Dr Tuba strut bladders are a saviour when you have problem with your kite bladder. It is a basic strut shape that you can add the correct valve too, building up a new one.
Measure the length of bladder you need and if not exact, go one bigger (Never smaller). You may be able to use your existing valve by sticking it on with Aquasure Glue or, for ease, pick the Dr Tuba replacement valve you need and simply make a hole in the blank and stick it on.
You can check how to do it in this sample video.