This rod holder eliminates fishing pole damage and rattling while underway. Commonly mounted in gunwale rod boxes, the round shape covers the hole and provides room for rod tips & guides to slide through. The one piece construction makes it easy to install, and the pliable radial grips flex to fit any size rod without damaging guides. Molded in U.V. stabilized vinyl. Can be mounted over up to a 3" hole, the pie-shaped grips hold your rod securely in the center. The top 2 wedges (or bottom, depending how you mount it) are hollowed out on the back to make it softer for guides. Also handy for use in passing wires and hoses through bulkheads. Mounts with 6 - #10 flat head screws (not included). This is the most common size & shape used by fishing boat builders for years. If your boat has plastic trim rings that have fallen apart, replace them with these to hold your rods and hide the hole! Dimensions: Diameter - 4" Flange - 3/8" thick (grips are thinner)Made in the USA !