I was so happy with my 1/4" foot....you just order one for a short shank Singer and it will work also on a 201 Singer as well as your 221 Featherweight :)
Judy in Phx, AZ
Maybe it's this http://theoldsewingmachineman.com/map.html
I use that foot on all my Singer low shank machines, also have one for my 301. Its a nice foot, can even use it on my Singer 237. I take the metal guide bar off the foot and like it much better.
I bought one of these on Tuesday from sew-classic.com. I'm waiting for it to arrive today. The prices are very good on this website.
I bought mine at Hancock Fabrics for my FW. Be sure to pay attention because it comes in a slant shank and a short shank. You want the short (straight) shank. It has a metal piece on it that you can butt your fabric against when sewing. It is a generic foot. If you have a coupon it can save you some money.
Oh THE very best 1/4" is one of the lowest priced ones. I have used the Apha foot, and other ones "they" say are good but they never held the fabric well.
I found that if you go and find a White low shank 1/4" foot it is the best and when I bought them they were only like $6 ea.
Don't waste your money on those hig cost ones..I know I have bought them all.