Among the many qualities of release mechanism boxes an important one is the absence of sharp edges, that could cut the dyneema or Nylon line.

A key aspect for the duration of the line, being it in dyneema or Nylon, especially in the area where the shaft enters the release mechanism box of the speargun, is the smoothness of edges, that could, if instead sharp, easily cut the line with time.

An easy check is the swiping of the Nylon line on the edges of the box. In the below video an excellent example of smoothed edges through tumbling process of the Salvimar Metal release mechanism box.