1/8" Rivet Diameter. 1/4" Rivet Head Diameter. Grip Range: 1/4" - 5/16". Body Material Carbon Steel. Open-end POP rivets, when set, resemble conventional tubular rivets. However unlike tubular rivets, the mandrel head is retained within the body of the Open-End POP Rivet. Providing strong, low cost fastenings, open-end rivets are ideal for a wide variety of applications. They are available in a wide variety of materials and combinations with dome, countersunk, or large-flange head styles. A universally accepted range of rivets suitable for most industrial riveting applications where the materials to be fastened do not have high load bearing requirements.