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 4140-01-020-4224
NSN 6240-01-633-9357
NSN 6620-01-504-5756
NSN 5950-01-455-1237
NSN 6135-00-505-0679
NSN 5985-01-630-2256
NSN 6130-00-297-5793
NSN 4140-01-608-7698
NSN 6685-01-274-9310
NSN 6220-00-719-7714
NSN 6240-01-411-3413
NSN 5855-01-093-8202