So theese guys on the Roof in takedown can't stay there forever.
Like. with a K-Style helmet, it looses durability when you get hit by a zombie or a player in the head.
For example:
James walks around in takedown with his lovely K-Style. he got shot 6times in the head by a m4 and it broke, so little james died because he afterwards got shot two times in the head with out the K-Style since it broke.