Zoll ( customs ) chin cord , need help please

[DRK]

Hello fellow collectors ,

I recently bought an untouched early Zoll ( customs ) visor at Ebay Germany.
Visor has a gold / green striped chin cord in combination with gold buttons.
Buttons and cord appeared to be Original to the visor ( there's some heavy green oxidation on the buttons pins underneath the leather sweatband , indicating they are there for a long time... ).

I'm looking for regulations regarding this chin cord , any help is much appreciated
Anyone who some info about these early customs chin cords ?
I will unveil more of this visor the coming days.....