Air versus Nitrox A Clamp

Can someone explain why there is a difference of £15 for a International A Clamp (Air) versus an Internationa A Clamp (Nitrox)

http://www.simplyscuba.com/ProductDetails.aspx?StockID=18295

What is in an A clamp that is sensitive to differing levels of O2.
At most an O Ring, and I cannot believe the O2 version of the O ring costs £15.

Why do I feel I am being ripped off here.

It's the whole 2nd stage that has different o-rings etc not just the clamp.

It does seem strange that Apeks are marketing another version for 40% Nitrox compatability however, as they always used to be fine out of the box for upto 40%.

If it was up to 100% then yes, I can see the need, but the blurb only mentions a Nitrox version.


EDIT: I've just had more of a look. In the 1st stage only section (of Simplyscubas site) it states for the DS4 and UST4 that the Nitrox version is for use with mixtures above 40%. I think the "Air" description is a bit misleading, if you only want it for backgas and not deco, the normal 'Air" one should be fine.

Regards

Just had a chat with them and it is as you thought. Up to 40% out of the box. if you want them to be )2 clean then you pay the extra.

[Visitor] Apecks XTX 200. Is the nitrox versions for O2 levels > 50%?
[Simply] yes thats correct
[Visitor] So the normal (air) version are ok upto 50%
[Simply] ?
[Simply] no just 100% air
[Simply] no nitrox at all on the standard version
[Visitor] so for 32% I need to buy the nitrox version
[Simply] for any amount of nitrox you wil need the nitrox model
[Simply] ooh.. wait.. i may be wrong, bare with me
[Visitor] Can you explain why? Apecks have, in the past, said that they are OK up to 40% or 50% out of the box. Above that they need to be O2 clean.
[Simply] ahh apolagies, i now understand your question
[Simply] yes up to 40 percent (really) they do not need to be 02 clean
[Simply] only cyclinders need to be O2 clean as there is danger of explosion otherwise
[Visitor] Thanks now I need to speak to the lady who holds the purse strings.