PacTool Snapper SS404 Fiber Cement Siding Shear with SA903 Siding Gecko Gauges Snapper Shear cuts fiber cement siding up to 5/16 inches thick smooth, fast, and eliminates airborne dust reversible blades machined from solid tool steel, and provide 20,000 feet of cutting SA903 made of Heavy-gauge plastic helps avoid marring the painted surface SA903 can adjusts in 1/4" increments for a 4"- 8" plus 8 1/2" reveal. Sold in a set of two. Can be used with 5/16 hardi-board.