MSA Cairns 880 Instrucciones De Instalación página 6

Installation
3.2 2-pt Chin Strap Replacement Kit for Helmet Models 660C Non-Defender,
664 Non-Defender
US
6
(1) Put the helmet on its crown on a flat surface or your lap,
so the front of the helmet points toward you.
(2) To remove the impact cap, pull on the rear overhead
suspension and push on the back brim.
(3) Use scissors to cut the old chin strap.
Note: Be careful not to cause damage to the plastic tubing
when you cut the old chin strap.
(4) Pull up on the overhead suspension to lift the plastic
tubing.
(5) Remove the old chin strap and discard it.
MSA Cairns Helmets - Chin Strap Replacement Kits