TRAKC MOUNT SIZE - Outer DIA: 28mm.Inner DIA: 16.2mm.Total L: 39mm .The dimensions of the nut plate is 29 x 13mm 316 Stainless steel material. Anti-rust even in salt water environment. Easy to Use, No need drill holes on the kayak. Easy to tighten, loosen or move and compatible with most track systems. These track mount tie down eyelets are suitable for fixing fishing pliers lanyard, paddle leash, fishing net, or other accessories to the track; Moreover, they are not only suitable for kayaking, but also for other objects with tracks, compatible with most track systems. Package Include: 4 Pack track mount tie down eyelet including Screw nut with tie eyelet spot X6, Base PadX6 and Bolt washer X12. Thorn Track Mount Tie Down Eyelets, M6 Metal Eye Bolts, 316 Stainless Steel, Hold Bungee Cord or Ropes Up to 0.6 Inch, Pack of 6