its a Q5 as well.
Not heard of a R5 before,
Aaaarghlblargh!
Q5, R5 and so on all refer to the luminosity bin-code that Cree use for their LEDs and does not denote the type of LED in any way!
Most lights labelled as "Q5" usually use the XR-E LED, which was Cree's breakout-product, and is now very antiquated.
Most lights labelled as "R5" use the XP-G LED, which has a larger die than the XR-E and XP-E and is therefor capable of handling more current at higher efficiency, so it goes higher up in Crees binning chart. There are also XM-L, XP-G2, XM-L2 and a whole host of other LEDs which are inappropriatly described by their binning code.
These Wiki articles provide a nice summary of all of Crees current interesting emitters;
http://flashlightwiki.com/Cree
http://flashlightwiki.com/Brightness_Bins
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