New to me.... the needle operation on this machine is different. Instead of just going up and down, this needle "walks" the project thru the machine, so the throat plate has a slot opening in it, not just a singe hole. The needle pierces the fabric and travels in conjunction with the feed dogs, moving the project one stitch back, and then returns into the start of the next stitch. Therefore, the extra feet that the seller provided me is NOT for this machine, which are also in the catalog previously (therefore erroneously)mentioned. Therefore, I guess you could call it a "walking needle" as opposed to a "walking foot".