Use for accurately checking the work of machine and toolmakers, the setting up of machinery, and other work that requires extreme level accuracy. The body of level is made of cast iron. Base is hand scraped for extreme accuracy. MASTER PRECISION LEVELSInchSize0.0002" per 10" Model No.0.0005" per 10" Model No.6"639-3606639-36168"639-3608639-361810"639-3610639-362012"639-3612639-3622MetricSize0.02mm per 1000mm Model No.0.05mm per 1000mm Model No.150mm639-3406639-3506200mm639-3408639-3508250mm639-3410639-3510300mm639-3412639-3512