kennametal 75 straight bore insertThe 75 Series is a boron carbide insert with a straight bore. The insert is suitable for blast guns and other holders with a cylindrical 3 4" insert format. Several bore sizes are available, from 1 8" (#2) up to 3 8" (#6), for fine to medium precision blasting and spot blasting. Boron carbide typically provides five to ten times longer service life than tungsten carbide when used with aggressive abrasives, such as aluminium oxide and selected mineral