One of the most common types of bobbins. Flat and taller than the Class 66 bobbins. Singer : 15 class, 233, 237, 239, 5102, 5107, 5122, 5123, 5124, 5127, 5522, 5528. Singer : 15-125, 15-30, 15-86, 15-87, 15-88, 15-90, 15-91, 15-96, 15-97, 15CL, 223, 227, 237, 239, 3001, 3002, 3003, 3004, 3005, 3011, 3012, 3013, 3014, 31-15, 331K1, 331K16, 331K4, 331K5, 331K6, 4001, 4002, 4005, 4006, 4009, 4011, 4012, 4015, 4016, 4019, 4022, 5102, 5107, 5123, 5127, 5502, 5504, 5505, 5508, 5522, 5524, 5525, 5528.
