Dritz - 4 Count Bobbin - Class 66 - Metal. For top drop-in bobbin cases. Consult your sewing manual to determine type of bobbin needed for your machine. Fits all Singer class 66 models and some of the following machines: Baby Lock, Brother and Simplicity. Bobbins not compatible with the following machines: Bernia, Elna, Husqvarna/Viking, Janome/New Home and Pfaff. Use only the same type (metal or plastic) of bobbin that came with your machine.