Review on Aquarium Standard Airline CO2 Proof Aquariums by Omar Allen

I asked what is the actual inner diameter of this hose "3/16.4mm"? I've tried it on 4 different diffusers and it slides and leaks easily! The bubbles will just come out where the end of the hose is, even when pushed 4 inches down the diffuser stem. Diffusers are different types of NEO that work great with a standard air hose, although it's not CO2 protected. Waiting patiently for the seller's response to my question/problem, but never received a reply Now it's been 3 days since the return period expired and I can't return it.