YYST 20 3/16" Deep Water Long Grip Tri-Grip Tri-Fold Tri Bulb Mounting Rivet - All Aluminum for Installing Kayak, Canoe and Boat Accessories 1. 20 aluminum rivets and 20 water proof O - rings. Free 2 card protectors 2. Material: ALL Aluminum No plastic. Aluminum Body with Aluminum Mandrel 3. Style: Tri-Grip rivet. Back Side splits in three directions for superior holding power. 4. 3/16" hole size. Rivet tool required for installation (not included) Grip 1/6" - 1/2" (4MM-12MM) 5. These rivets will work great on almost any application on kayak like rod holders, pad eyes, terminal ends, handles, etc.