Pool hoses, 30-40 fitting

Pool pipes, 30-40 connectionI needed to join two corrugated pipes from my INTEX swimming pool. One has an internal diameter of 3 mm, the other 40 mm.They are guys who take water from the pool and take it to the pump. My bottom brush has a small tube, the water intake from the pump is large. This seemed like a simple solution.The central ring is only used to help insert the accessory into the tubes.I printed it "lying down" since I wasn't interested in quality but resistance, I insert