The Moore & Wright MW500-01 Universal 360 degree Bevel Protractor is made from high quality hardened and ground stainless steel and has a high precision satin chromed scale. It is fitted with a magnifying glass for easy reading with a fine adjustment and height gauge attachment. They have miniumum reading time of 5 minutes, this is a visual angle of 5 arc minutes (1 arc min - 1/60 of a degree).