[Roberts]

The screw type master link has special nuts to press the side plate onto the master link pins. After the side plate has been pressed all the way onto the pins, the special nuts are removed. The protruding pins are then snapped off at the notch. The small "O" rings fit into the grooves outboard of the sideplate (or safety wire can be used). This patented link eliminates the need for expensive riveting tools, an 8mm wrench and pair of pliers are all that is needed.

Safety wire needed.