Replaces Part Numbers: 4006 710 2126?4006 710 2106, 4006 710 2140? 4006 710 2103. For Stihl AutoCut C6-2 Trimmer Head Compatible Models: For Sti-hl FS38, FS40 (2000 On), FS40C, FS45, FS46, FS50 (2000 On), FS50C, FSE60, FSE71, FSE81, FSA60R, FSA86R. FSE60 FSE71 FSE81 FS38 FS40 (current model - 2007, not previous version - 2000 years ago); for Sti-hl FS46; for Sti-hl FS50 Applications: C6-2 weed eater head use for Lawn mowing, around trees, between shrubs along edges, walls and fences. Easily loaded by inserting line holes and rotating knobs