3 Arm Replacement Stones for Engine Cylinder Hone 400 Grit 4" Long X 5/8 Wide Stone w/ holder dimensions: 4" L x 5/8" W x 3/4" H 400 grit Aluminum oxide stones bonded to aluminum stone holder Fits most models of 3 arm hones including PMD Products, KD, Harbor Freight and Greatneck (OEM) Can use with other engine cylinder hones with 5/8" stone mounts Replacement stone holder is 5/8" wide with bonded stone 1/2" wide