Infiniter Rs-1 Laser Cutting Guide Fits most 7-1/4", 8", 10" and 12" miter/chop/cutoff and hand held circular saws. Powered by three alkaline batteries (included). Easy to install! Ideal for most large-field cutting. Lightweight (2.12 oz) portable features make for easy installation and operation. Produces a bright(30 feet), easy-to-see line for dead-on accurate cuts. The RS-1 does not fit Delta Shopmaster cut-off saw and 7 1/4th inch black & Decker saw