Oregon 55-140-0 Trimmer Head Magnum Gatorhead, Heavy Duty, 4" 4" heavy duty head Pre loaded with trimmer line Counterbore hardware Recess adaptor bolts and recessed base Adaptors included: 8mm x 1.25 Left-hand male and female, 10 mm x 1.25 Left-hand male and female, 10mm x 1.0 Left-hand female, 7mm x 1.0 Left-hand male