Nike+ Fuelband Sizing Help- Which size Fuelband should I buy?
A little help for those trying to figure out UK Fuelband sizes

:-
Small fits
most women
Medium in UK (Renamed Medium/Large in US) fits
most men
Large in UK (Renamed Extra Large in US) fits
bigger men
And a bit more detail, the basic sizes of the bracelets
before you add an additional link are:-
UK Small is 5.79 inches/ 147 mm
UK Medium is 6.77 inches/ 172 mm
UK Large is 7.76 inches/ 197 mm
With the
smaller link attached these become:-
UK Small 6.09 inches/ 155 mm
UK Medium 7.07 inches/ 180 mm
UK Large 8.06 inches/ 205 mm
With the
larger link attached these become:-
UK Small 6.39 inches/ 163 mm
UK Medium 7.37 inches/ 188 mm
UK Large 8.36 inches/ 213 mm
As a normal sized UK female, I chose a UK Small which is a very snug fit with the smaller link but also gives a very comfy fit with the larger link, which is how I choose to wear it. I think the bands have been designed so that there is a bit of flexibility there so each size actually fits a range of different sized wrists. If in doubt, I would go for a small as a female, and a medium as a male unless you're a big guy, then go for the biggest size. Hope this helps!