Glued in place with epoxy, these lightweight arbors create a super strong bond between the reel seat and the rod blank that increases sensitivity. The arbor is a solid, semi-porous polyurethane material that is machined to fit most sizes of reel seats and can be turned down to fit between sizes. All arbors have a 1/4" inside diameter pilot hole which can be easily reamed or drilled out to fit any rod blank. 16mm for Real Seat .595" OD x 3.80" 17mm for Real Seat .665" OD x 4.20" 18mm for Real Seat .700" OD x 4.25" 20mm for Real Seat .780" OD x 4.38" 22mm for Real Seat .855" OD x 4.75" 24mm for Real Seat .930" OD x 4.75"