Simms Hardbite Studs for Vibram soles are 45+ Rockwell hard screws, zinc plated for corrosion resistance, with welded carbide gripper pellets for enhanced traction. The 1/4" hex had fits any standard nut driver, and the package contains a small nut driver for convenient installation. Simms Hardbite studs are easy to install, easy to remove. 24 per package.