I've studied them. Some things to consider..
#1 your machine.... how deep is the throat? this is reccommended for a minimum throat of 6-9 inches ( darn it mine is right at 6 inches)
#2 are these advertised fro sale, the old style or or the new? old style = u use wooden dowels, new style u use light wt fiberglass/pvc or metal--- this could mean a big wt difference ( they connect to the frame a bit differently)
U can purchase the adaptor kit to convert the rails, but thats an additional $20-30 bucks)
#3 do they come with the " extension rollers" ( PVC pipe that act as a extention table , so that u are not having to hold up the entire length of the frame that is not under the needle.
http://www.flynnquilt.com/
good luck