don't know the contour 3.3 screw-in thread metrics but here's what i do when i need something like this. take out one of the supplied screw-in feet. visit loew's or a similarly well-equipped hardware store. check in the nut bins 'til you find one that will fit your foot. then figure, by label or more trial-and error, the bolt that fits the nut. the bolt should be labeled by diameter (sae or metric) and thread count (per inch or cm). now you have the info to order your bdr screw-ins. maybe kinda tedious but it works. -kelly
