HEAVY DUTY ACRYLIC SPEAKER BOX TERMINAL 
Semi Transparent(smoked) 1/2 Plexiglass with (8) 3/16" Countersunk mounting holes around the perimeter & (2) Grade8 5/16" Bolts with lock washers.. 100% HAND MADE IN THE USA! . 
 
Terminal Dimensions- 
Thickness- 1/2"
Outer Diameter- 3 3/4"
Inner Cutout Diameter- 2 5/8"
Bolt Size- 5/16" x 1 1/2"
Mounting Screw Hole Size- 3/16"