The correct rinks should be stable without these metal elements. The rinks should disconnect when absorbing a strong hit - the parts should be partially separated, moved away and thus they help to slow down the hit. Unfortunately, it does not happen when a fixed joint is used. The impacts to the rinks are harder. Some manufacturers use plastic bolt joints, others plastic hooks. These kind of joints might be too fixed - when a player hits the rinks they are not disconnected. This is quite a risky element, we recommend to replaced it by a "flexible joint". This is the best option of joining the rinks, which contributes the safety to all the participants. In principle, an elastic stretch rubber is used for the connection, which streches when players hits the rinks. So the rink parts spread apart.