I bought the "fabulous fabric glide"...
http://www.createforless.com/The+Gyp...FbFAMgodKDYAqQ
they are just about the same as the martelli, but cheaper....they have little rubber knobby points on the underside that grip your fabric. I don't use them..they work ok, just like on the video, but I never could get used to not having my hands on the quilt! I was constantly stopping and checking to see if I had a fold or a ripple on the back...I never could understand why they sell 2 in a package! the difference in size is less than an inch...maybe 2 people could buy one set and split the cost..that would make them super affordable!