FEATURES: Made of steel, hardened to Rc 58-60. Gage block roll has (2) .200" minute steps for setting small angles with standard gage block sets. A locking strap that always remains below the top surface and two self-storing, hardened and ground rails are standard. Angular accuracy guaranteed within 5 seconds of arc up to 15°, within 10 seconds up to 30°, & within 15 seconds up to 45°. Not SineSet® Compatible. SP555 SUBURBAN SINE PLATE