I have them also as they came with my frame, they are to help when centering your pieces on when loading but when I put a real tape measure to them they must have been stretched as they where not correct. I ended up taking a sharpies and marking my own reference points and bought the quick zip system. I love it as I can pin a quilt on while watching tv and if I don't like what I am working on all I have to do is zip it off and load another without having to undo all those finger sticking lilttle pins...lol