PTFE tub cap with tether

This is a remix of henryarnold's PTFE tube cap. I like his cap, they work well, but I kept miss placing the darn things since they were a loose piece.
I redrew the cap adding a tether that slips onto the PTFE tubing. No more loosing the cap.
I printed the caps and tether in TPU so there was a nice tight fit and good flex in the tether.

The caps are for 1/4" PTFE tubing only. I didn't have a piece of 4mm PTFE to check the measurements. I would think they will work with 4mm tubing if resized.