Wetta Barb to Hose End Joiner Clip use these fittings to join or repair a 13 mm length of hose (internal diameter). They are extremely strong one piece. They can only be used for joining hoses of the same diameter. Fitting could not be simpler. Push the hose pipe ends over the barbed tails as far as they will go. This will normally suffice for normal or gravity fed water pressure. TIP If you are having difficulty pushing the hose over the barbs, try soaking the end of the hose in hot water for a few minutes. This will soften the material and make fitting easier. when cool the hose will shrink down to form a tight seal with the hose tail.