MR THOMAS M K The power inflator fits the standard inflator hose Zeagle uses on its Ranger model. That hose appears to be of a standard size used on all BCs, I would guess about 3/4 inch or maybe 1 inch. I'd suggest contacting Zeagle if you need to know the diameter more precisely. The inflator works fine, the biggest advantage is it makes bladder rinsing easy.