FNG,
DC K-Series helmets - an inner cloth/mesh suspension liner that a
'standard' 10-* series DC headset will fit into, which then
snaps into a thick plastic helmet shell. The snap connectors
are a sod though - even after reading the instructions
and working out they're directional - so it's not a 2 minute
job to install and remove the headset. Fairly light, after
a while you don't notice wearing it during aeros. For
what it is, a bit pricey - I shipped mine in from the US, and
even after DHL caught up with me for duty, still cheaper
than buying in the UK. Not sure about how much head protection
they would give over a 'proper' helmet, but they do stop
your headset falling off in negative G, which was the point
of the exercise, and I assume would give more head protection
than a cloth helmet. Oh, and deeply unflattering appearance.
Ed.