8acrylic plastic, mil-p-5425, stock size 3.000 in. Lg, 2.200 in.W, 0.250 in. Thk, mfr in a/w mil-p-7788 except omit par 3.3.8, 3.5 and3.7--in par 3.3.2, 3.3.3 and 3.3.5 substitute gray color no. 3520per specification tt-c-595 for black, center aperture 1.875 in. Dia