This listing is for a Complete Gear Set consists of :

163328 Top Gear, 

174204 Lower vertical, 

163996 Timing gear, 

163997 Hook drive gear

163329 Hook gear

fits SINGER Sewing Machine Models 620, 625, 626, 628, 629, 630, 635, 636, 638, 639, 640, 645, 646, 648, 649, Touch & Sew and more.