This is a PETG adapter to connect extend a hose or gap a removed part because of a hole. It is quite tight and has many different positions to squash the hose in place between the rail and the ring.
The hose in the picture above as about 0.2mm thickness and radius of about 5-6mm. If you add the adapter I've tested it with 2.5 bar and it only had a very small leackage.
I've been using
I created this for a friend because there were no such adapters and he often needs to put together different ends of hoses.
I've added the source files in freeCad, was a hazzle to create those but here it is!
The author hasn't provided the model origin yet.