Atlas didn't allow the sky to dangle freely; he won't let your helmet do so either. 
 
Sometimes on long rucks, you don't want to wear your helmet, but chin strapping to molle and letting it hang and swing for miles is not only annoying but also fatiguing. 
 
Atlas keeps a helmet or anything that fits secure against the back of your pack without the sway. 
 
Secure the bottom with the Tigris through molle on the bottom and the top straps and then buckle and tighten to the needed size 
 
NOTE: Specifically designed to work with laser cut Molle