Plug for the filament sensor hole in the back of the K1/K1C/K1 Max where the bowden tube comes through.  Useful if you have reloctaed the filament runout sensor like I did and was looking to plug any holes were hot air could escape.

I printed mine in TPU just so it was a little bit flexible and would “smush” into the hole.  Therefore this has been designed to be a little bit bigger than the hole size actually is.  If you print this in a none flexible you might need to scale it down a bit.