Parts Express Heavy Duty Speaker Grill Guides 12 Pair Ball and socket type grill guides for attaching speaker grill to cabinet. To use, simply drill the appropriate size holes in cabinet and grill frame. Both portions press-fit into their appropriate holes. 12 pair per package. Hole dimensions: 7/16' for the ball, 1/2' depth. 9/16' for socket into cabinet, 1/2' depth.