Fits Pfaff models 1016 Hobby, 1020 Hobby, 1030 Hobby, 1040 Hobby, 139, 204, 205, 206, 207, 208, 209, 210, 211, 213, 301 Hobby, 303 Hobby, 307 Hobby, 4240, 4250, 4260, 521 Hobby, 541 Hobby, 721 Hobby, 741, Hobby 1022, Hobby 1032, Hobby 1042

Bobbins measures 7/16" thick x 13/16" wide.