Stens 385-897 Pivotrim Universal Trimmer Head Arbor sizes included: 5/16 x 24 RHF, 3/8 x 24 RHF, 7/16 x 20 RHF, 8mm x 1.25 LHF, 8mm x 1.25 RHF, 10mm x 1.00 LHF, 10mm x 1.25 LHF, 10mm x 1.50 LHF, 12mm x 1.50 LHF, 12mm x 1.75 LHF, 5/16 x 18 RHM, 8m Classic, Uses .095" diameter line; Easy installation Less stops to change line, Quick easy line loads, Prevents broken lines, Easy installation, Ideal for consumer and commercial use Recommended for trimmers under 25cc; Up to 8 cutting edges Fits 99% of curved shaft gas trimmers; Replaces Old Part Number: 385-857