Cut the tubing in a long diagonal with scissors.
This is an optional feature and can be used for any hoop. This tubing can be found at almost any decent hardware or building supply outlet.
The long diagonal cut makes a tighter fit and an attractive design as well.
The ribbed sleeve feature can be easily added to any size hoop and holds a bit more juice than without.
Ribbed sleeve demonstration video
Demonstrating the ribbed sleeve option (Note: I ran out of room as I was backing up in this video or it would have been a much longer tube)