To be able to attach a back of head protection, the economy or SPES, you need to extend the length of the back strap of the PBT mask. Its a velcro strap, and this will give you the extra length needed.
We have also used it to extend the velcro straps on the AF chest protector. If you want a short size, but are wider than normal, the straps may come up a couple inches short, this will help.
