Split ring

A split ring (or key ring) is a cylindrical piece of metal shaped into a multiple looped circle with a kink in it.

The kink allows the ends to sit almost flush against one another but seperated by the kink.

This allows closed objects (commonly hoops of some sort) to be secured inside the split ring.

The kinked section of a split ring

       |X||X|
       |X||X|
       |X||X|
 End-- |E///---Kink.
       |////| 
        ///E| --End.
       |X||X| 
       |X||X|