The below is taken from the NZDRA rulebook
Helmets:
5.57.1 Requirements Protective helmets shall; a. comply with a standard below , b. be a good fit on the wearer so they are secure when worn.
Note: The helmet must not be able to be removed by lifting the back of the helmet.
i. be in good condition, and d. not be modified, except as specifically permitted by the helmet manufacturer, in particular;
ii. ABS and Polycarbonate helmets cannot be painted,
iii. composite shell helmets may only be painted with a paint approved by the helmet manufacturer, intercom earphones and microphones should only be fitted in helmets specifically designed for their fitting. In all cases, when fitting speaker(s), care must be taken to ensure that they do not create a hazard for the wearer.
Standards:
Cars slower than 11.00 seconds, and open or full face helmet meeting one of the following standards: SNELL SA2005, SA2010, SA2015, SA2020, SA2025, M2005,M2010,M2015, SFI 31.1, SFI41.1, or FIA 8860-2004, 8860-2010, AS/NZS 1698:2006, AS or NZS 1698 or European Standard (R22);‘E’ Mark, 02, 03, 04 or 05 series