Yes, it is a Singer 221. I have used low shank attachments on other machines wilth out any trouble as they have all been similar between my Brother and Sears/ Janome machines. This zig zag attachment is just so neat. Maybe I need to get a Kenmore "58" to use it on. Nothing like buying the attachment and them looking for a machine. I think the machine was made by White for Sears in 1956. Ismac had something about it.