Roller chain is normally used as a continuous length. To complate that continuos length you can use a connecting link. The connections that are available are cotter pin and spring clip. For the lighter weight chains in single and double strands both options are available (#60 and smaller), once you get to the heavier chains the cotter pin is your typical option especially when you move to the triple and quadruple stands. Standard connecting links have a slip fit cover plate which slide on to the face of the connecting link. it is then secured by the spring clip or cotter pin.