Shell, kit, helmet and methods of manufacture of a shell

A helmet comprising a helmet hard shell and a shell configured to be detachably attached to the outside of the helmet hard shell, the shell comprising:

• a first region;
• a second region;
• and
• a plurality of openings, each of the plurality of openings extending from a first side to a second side of the shell;
• wherein
• the plurality of openings are arranged along a boundary between the first region and the second region, the shell is arranged outwards of the helmet hard shell such that the shell directly contacts the helmet hard shell under forces associated with an impact, and a sliding interface is provided between the shell and the helmet hard shell;
• the shell further comprises a lip portion extending over the edge of the helmet hard shell, wherein the lip portion extending over the edge of the helmet hard shell is configured to detachably attach the shell to the helmet hard shell;
• and
• the lip portion extends over the edge of the helmet hard shell around the entire periphery of the helmet hard shell.