This is a New Feed Dog # 12481 + Needle plate # 12482 that fits the following models. 

This feed dog will only work with the matching needle plate.

for SINGER MODELS - Class 31, 31-15, 31-17, 31-18, 31-19, 31-20, 31-29, 331K, 44 220U2, 220U3, 191D200A, 191D300A, 431F200A, 491D200GA, 491D300GA, 591D200A, 591D300A, 1191D300A, 1591D300B, 1591D310B, 1591D300G, 1591D310G.