Superior Transmission Products Bench Buddy 4 Brush Kit T-BB100 Impregnated with a special super fine abrasive, Bench Buddy brushes easily remove small burrs and polish the inside of a valve bore with virtually no enlargement of the bore diameter itself. Each Bench Buddy kit features 4 different sized brushes. * Improves the surface finish of a bore by up to 50% * Restore smooth valve operation in seconds * Services bores from 1/4" to 1" Brush Size 1" use in bores 3/4-1.0" Brush Size 5/8" use in bores 5/8-1/2" Brush Size 1/2" use in bores 1/2-3/8" Brush Size 3/8" use in bores 3/8-1/4"