One visor fits all the G4 helmet sizes, with an anti-fog inside and anti-scratch outside. Your choice of clear, dark tint, blue or orange mirror. The G4 visor is tested for its optical qualities, and as such it has been certified and carries a CE mark.
The visor is very simple to remove. Undo the two side plates screws on both side of the visor. Remove these plates and slide the visor forward. The tinted and mirrored visors are certified to Category 2 against ISO 12312-1:2013.