A trimmer head tough enough for Rino line. Simply bump to extend line. Designed to fit 90% of trimmers. For both consumer and commercial use. Recommended for trimmers 21cc and higher. Includes the following mounting bolts: 10 x 1.25 Female Left Hand., 8 x 1.25 Female Right Hand, 5/16 x 24 Female Right Hand, 7/16 x 20 Female Right Hand, 3/8 x 24 Female Right Hand, 8 x 1.25 Male Right Hand, 8 x 1.25 Female Left Hand., 7 x 1.0 Male Left Hand., 10 x 1.0 Female Left Hand, 10 x 1.25 Male Left Hand.