A precisely calibrated instrument used as a master reference standard to establish an absolute horizontal plane. The metal base is seasoned and heat treated or otherwise specially treated to insure maximum stability, and is accurately machined and scraped to the true plane on the contact surface. The top plate is of nonconductive heat insulating material. It has a very sensitive vial graduated to indicate a variation of 0.0005 inch (0.0127 mm) per foot (0.3048 m) in a horizontal plane. It may have a cross level vial to assist in setting the true horizontal by showing position laterally.
Classification: Other measuring or checking instruments, appliances and machines, nesoi in chapter 90
NSN 6645-00-873-4642
NSN 5835-00-143-4153
NSN 6240-01-176-9037
NSN 5975-00-040-2363
NSN 6150-01-611-4752
NSN 5960-01-065-0273
NSN 5930-01-539-6375
NSN 6610-00-477-7931
NSN 5965-01-477-6665
NSN 5930-01-400-0892
NSN 6135-00-708-0892
NSN 6620-01-375-0211