Button head Una drive bolts have an internal hex socket drive in the threaded end to hold the bolt steady while tightening and securing nuts. The button head design helps prevent tampering, and it also distributes the load over a large area for added joint strength. These bolts are coated in a phosphate and oil finish to prohibit rust in wet environments.

Built to assemble freight cars, Grade 8 camrail bolts or freight cart bolts are typically used in wear plates, carrier plates, center plates, bearing retainer keys, corner caps, and side bearings. Button-head camrail bolts with AudiTorx drive are designed to shear off when proper torque is achieved, leaving a tamper-proof button head for secure installation. These bolts are designed specifically for maintenance and repair use in locomotive applications. These bolts come in a black oxide finish, which is corrosion resistant in dry environments.