Steel, sheet, corrosion resisting, class 302-a, finish no. 2b, spec qq-s-766; outside oval dimensions are 1.37 in. X 1.03 in; inside oval dimensions are 1.00 in. X 0.67 in; a notched section on the outer surface is 0.100 in. Wide by 0.085 in. Deep; cup outer electronics for mine at he m75