This three speed bobbin is clear lacquered to match the finish of the S10, S10DT and S51, S51DT wheels but will fit the S17, S15 and S75 as well. The bobbin has a sheave with three settings on one end to obtain three different spinning speeds. The ratio's for these wheels are controlled by the bobbin and are: 5.5:1 for slow spinning and heavy yarn; 7.5:1 for medium yarn; and, 10.5:1 for fast spinning and fine yarn.
Bobbins will hold approximately 6.3 ounces to 8.8 ounces (180-250g) of yarn - a very large capacity.