Bobbin Winder Thread Guide Sp15366ring - Singer Part # 15366
-Bobbin winder thread guide spring.
-Part # 15366
-Fits Singer models 66, 99, 115, 15-30
-Outside diameter of spring is a little less the 3/8"
-(Note) Measure the outside diameter or your old spring. These will not fit some of the early 66 models.