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 5985-00-337-6819
NSN 5965-01-008-8712
NSN 5920-01-512-0713
NSN 4140-01-295-8264
NSN 5935-01-296-2601
NSN 4140-00-127-5311
NSN 5965-01-451-7313
NSN 5930-00-278-7731
NSN 6150-01-357-2451
NSN 6320-01-317-7312
NSN 6620-01-437-3146
NSN 4140-00-930-4673