I can't get my System 5 in but my wife csan get her, smaller, one in.
In any case I can't recommend this box as mine came adrift from the bike on Stelvio Pass., It was replaced under warranty but I beleive this is not an unusual problem so find it hard to trust the replacement.,
Agree but in practice we have not found it a major problem. When touring all our boxes are full of luggage so we couldn't use them for helmets anyway. Last year we bought two Paksafe helmet bags which is a better solution.
These bags have a 'helmet friendly' fleece liner, a waterproof outer and a stainless steel netting in between. A steel cable goes around the open end and through the netting. It takes seconds to drop in the lid, pull the cable closed and lock it to the bike. The closed end of the bag has a velcro loop so it can hang on bars or frame with open end down to keep rain out.
To steal the helmet it would neccessary to either break the lock, cut the cable or cut through most of the netting so its probably harder to nick a helmet from one of these than to break the Mickey Mouse locks on top boxes. With the Vario top box it would not be hard to lever the whole box off the bike.
They fold to about the size of a Coke can so are convenient to carry when the bike is used without luggage fitted.
My wife also carries a Paksafe luggage net which is designed for rucksacks but goes over the soft luggage fitted to her CS. It secures the luggage and has space to get our jackets inside when sightseeing in hot weather.
Cfm Size 61 won't fit.
Cfm new boxes have a different design of lock onto the table and Ifailed to shake mine off in 5000kms trip here recently.
Saw a box fly off before and stayed away until Iknew the new design was ok.
Bin
The RHS box on the wide setting is good for helmet.
When travelling, I pack clothes in a bag in that pannier, and when at the digs, I take that bag in with me, leaving the helmet in the empty box.
Result!