Brand: OMP Racing Products
This net from OMP lets you and your navigator store your helmets safely between rally stages. An adjustable strap at each corner wraps around your rollcage main hoop and rear supports.* Two pockets each hold one helmet, preventing them from rolling around the floor and getting damaged. Unlike helmet hooks, your helmet isn't likely to swing far enough to hit the windshield (or the back of your head).
Silver-grey with black webbing straps. Weighs less than 2 pounds and takes up almost no room -- better than carrying around your original cardboard box (and safer, too)!
* You may need to add some kind of a retainer (such as a hose clamp) to keep the net from sliding down the tubes, depending on your cage design.