Plastic, black; center aperture, 0.500 in. Lg by 0.500 in. W on top, graduated to 0.438 in. Lg by 0.438 in. W at bottom; slot both ends 0.125 in. Lg by 0.125 in. W on top and 0.250 in. Lg by 0.250 in. W on bottom; o/a 2.188 in. Lg; 0.512 in. W; 0.125 in. Thk