"USED TO CHECK/SET PWA71574 GAGE TO ""ZERO"" BY REPRESENTING THE DIFFUSER CASE REAR FLANGE INNER/OUTER SNAP DIA;INNER DIA: 26.792 PORM 0.0002 IN; OUTER DIA: 26.892 PORM 0.0002 IN; CONSISTS OF A STEEL BAR W/ UPPER GAGE PLATFORM; SUPPORT POSTS HAVE STEPPED CONTACT BLOCKS DOWELED AND BOLTED TO THE TOP SURFACE OF EACH END; OVDIM: 2.0IN X 4.0IN X 28.0IN"