12" CONTRACTOR ALUM. RAFTER SQUARE W/MANUALAs a saw guide stair layout tool or rafter tool Johnson s 12 rafter square will help you get the job done accurately and easily. Its solid aluminum body construction with CNC machined edges provide greater accuracy and durability while the low glare protective powder coated finish makes the permanent graduations and numbers easy to read. This square also features scribe notches starting at 1 3 4 that are useful when transferring outside increments