In reply to Graeme Hammond:
> For those that don't know it might be worth including a table about what the different categories mean, particularly as "category 4 lenses only transmit between 3% and 8% of light and are not suitable for driving at any time. Sunglasses with these lenses should, by law, be labelled 'Not suitable for driving and road use'" - source AA website.
I'm never quite convinced what 3% to 8% actually means to anyone, because it certainly doesn't mean anything to me. To put it another way, but has anyone ever walked into Outside and asked for a pair of sunglasses that have a 5% transmission rate? I suspect the answer is a resounding 'no' - they come in asking for a pair of sunglasses for use within the Alpine environment (or whatever else they're looking for). As a result, what I went into detail on were the practical differences in between the various categories and their usage, because that - at least from a laymans perspective - is something that everyone can understand.
I was also convinced that I'd mentioned driving, but that must have been edited out somewhere along the line (which is strange, given that it's actually a serious point). Due to the Reactiv nature of the glasses, the chances of them actually 'reacting' up to category 4 whilst you're driving is very, very unlikely, as there's simply not enough light (on a glacier, in the sun, yes; in a car, no...). Comparing them to my previous Cat. 4 Julbos side-by-side there's a marked difference in how much light they let through, particularly in the shade - hence driving in them isn't a problem.
Post edited at 09:31