Notice this component has been added to foundation model Size A Helmet - contemplate this matter deprecated.
It is an LED mount for the back insert in this full size A Halo Helmet.
This insert takes two 5mm Leds into the base of the bit.
The body is deeper to take the leds and diffuse the light somewhat.
All designed in Autodesk Fusion 360
10% infill, standard profile, 2 shells.