Tested and used all over the United States for the past 20 years. The collar is 1/4" thick polyethylene plastic. It is reinforced in the center with a PVC compression coupler welded in.
The pipe is placed through the compression coupler and tightened on both sides with a compression nut.
Collars can be built for 1/2" - 3/4" - 1" - 11/2" - 2" and 3" diameter pipe.