This is really one piece Summit for the Halo Helmet Full Size A ( http://www.thingiverse.com/thing:158120 ) that's added mounts for 9V Batteries.
Just one battery is necessary for LEDs that were current but you never understand.
Printed nicely and batteries "snick" in.
Though note this can hold a Duracell but some other no-names are somewhat smaller.
Left and right summits divide for smaller beds.