There is a kind of joint for you to connect hose of different diameter. The 2 ends is in a form of stepped cone. Each side has 3 steps, the mouth has a smallest diameter and the more inner step is biggest.
So if the hose diameter is small, it will fit the smallest step at the mouth. If its dia is big, it will fit the larger step further in.
There are 3 type of hose size: 12/9, 16/12 and 22/16. That's the hose outer/inner diameter. So make sure you know your hose size before purchasing the joint. Normally the joint can fit all 3 size.
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