Prevents calculation errors when producing mitre joints or single cuts. Upside down or backwards, the reading is always correct Simply set your circular saw to the angle read from the laser engraved scale for 100 percent accuracy Made from hardened plastic with the same smooth and precise operation as the Aluminium models This product is ideal for joiner's/carpenter's, plumber's and building trades that require the measuring and transferring of angles The Pro-Site Protractor saves you time and money by simply reducing waste