It is a 12" x 18" of "plastic" (for lack of a better term), that adheres temporarily to the bed of your machine with the needlehole opening. It is slippery and aids in free-motion quilting. Supposedly, there is no drag caused by humidity or whatever. I recall that it is very thin, but I do not know the composition of the sheet. Once positioned, it will not slide around until you lift after use.
Just thought someone in the group had tried same.
Suzanne