The tape applies easily and is very forgiving. It can be peeled back and reapplied repeatedly. After a few hours it gets a bit harder to remove, but is still easily removable.
The tape provides a firm surface for compression rings to tighten against. I can report that it works very well! Prior to the tape, my eyepieces would sit loose in my Binotron-27. It drove me a crazy and affected the collimation of the images. After the tape, the eyepieces sit squarely and firmly.
If undercuts bother you, you might consider doing this. It only takes a few minutes, and if you don't like it, it's easy to remove before it dries.
Edited by shams42, 02 August 2015 - 05:01 PM.