Now comes as a six pack. New Photo Comming Soon! Push Rivets, aka Pine Tree Rivets. 5/8 in. long, ¾ in. head. Round ridges, 5/16 diameter shank, pointed end. Common on some Wilderness Systems Tarpon kayak seat pads and Perception kayaks outfitted Zone Seating. Used for Knee Pad Kits on recreational Perception brand kayaks. Will fit into a .25 in. drilled hole. (alt part numbers; 3070020, 9820103, Harmony Plastic Push Rivet 0.61 in. Diameter - 6 pack 9800427, ITW 39065005-04004D)
This type of mounting hardware is typically used for a pre molded or pre drilled hole. Commonly used for seat pads, and other kayak features like side net bags and thigh pads. The ridges on the shank will fit very snuggly into the hole and resist removal. Insertion is easy, removal may require some prying and pulling with hand tools and probably damage the rivet.