THIS IS FOR (QTY 2) MDF 5.25 INCH SPEAKER RING INSIDE DIAMETER --- 4 5/8 INCHES OUTSIDE DIAMETER ---- 5 11/16 INCHES THICKNESS -- 3/4 ALL RINGS ARE MACHINED FOR PERFECT ACCURACY PLEASE CONTACT US FOR CUSTOM CUT RINGS & SIZES WE HAVE MULTIPLE MDF RING SIZES & STYLES THESE ARE GREAT FOR BUILDING FIBERGLASS BOXES, CUSTOM SPACERS