Parallel to the flat foot is the standard by JB/T7977-99 manufactured materials for the HT250, the word square feet of working face using scraping or grinding precision, for machine tool inspection and testing roughness degree two face is not straight with block gauges, micrometers, levels and other equipment inspection, different heights, two parallel rails and not the level of rail connections, and can scale with the right angle, right angle foot test can only test two parts of the verticality of the gauge, word square feet also work for equipment installation and inspection, temperature (20 ± 5) ℃ 
 Jeans square feet (parallel to the flat feet) Specifications: (mm) 
 500 × 35,750 × 40,1000 × 50,1200 × 50,1500 × 70,2000 × 80,2500 × 80,3000 × 100,3500 × 100,4000 × 10