"ALUMINUM ALLOY QQ-A-250/12 7075 TEMPER T6,2.120 IN. O/A LG,1.500 IN. O/A W,0.247 IN. MIN TO 0.263 IN. MAX THK,MACHINED SURFACES 250.0MICROINCH FINISH,3 MTG HOLES 0.193 IN. MIN TO 0.199 IN. MAX DIA,2 HOLES 0.251 IN. MIN TO 0.258 IN. MAX DIA COUNTERSUNK FOR SCREW NO. NAS517-4"