Gosling1 wrote:those buttons are a pain in the arse and I cut them off my chin straps - then stitch the end of the strap up to stop it fraying. They are only there to stop the strap from flapping around the place - as pointed out already, as long as the D-rings are still in good nick, these buttons are not a structural fitting.

Confirmed as per what Gos said - not a structural retention fitting of importance,
Strength of retention system.
When the helmet is tested in accordance with AS/NZS 2512.5.1, with a preliminary
test loading of 225 ±5 N applied for 30 s, and an additional loading of 1110 ±25 N
applied for 120 s, the retention system or its attachments shall not separate, and
the elongation between pre-loading and test loading shall not exceed 25 mm.
Where the retention system consists of components which can be independently
fastened without securing the complete assembly, each such component shall
independently comply with the requirements of this clause.
PS--- My helmets have passed impact and penetration tests now, the two most important ones --- few more to do and all those that complain about a sore neck etc after a long ride will be able to rectify that issue.