http://www.april1930s.com/html/quilt...tachments.html Any short shank 1/4 foot should work, but April specializes in FWs and 301s. The magnetic guide won't stick on an aluminum machine (301 and FW) and actually shifts over time on a steel machine.
I have a 1/4" foot for my 301, but prefer the screw on metal guide. Mine has to sit on a screw head, but the head is flush with the bed of the machine so it doesn't matter.