Is it possibly this one that's believed to be a 20-ampere constant rated LG?
http://lygte-info.dk/review/batteries2012/Efest%20IMR18650%202500mAh%20(Purple)%202014%20UK.html
http://www.akkula.fi/efest-18650-IMR-2500-mAh-Purple
It's good. It's also mislabeled and overrated by Efest. Interestingly on this one there is quite a small difference between flat and button tops, but it's there.