Rock Tumbler Grit for 15 pound Tumbler 4 step grit pack and instruction set for one time use in a 15 pound barrel. 1 pound 60/90 Coarse Silicon Carbide Grit. 1 pound 150/220 Medium Silicon Carbide Grit. 8 ounces 500 Fine (pre polish) Silicon Carbide Grit. 8 ounces TXP Aluminum Oxide Polish.