I have been looking on Ebay for a charger and 8, 3.7v 18650 batteries for my new Fenix TK75 and have seen the ultrafire batteries with up to 4900mah. Is this size/capacity the way to go or should I stick with the lower 3000mah? Also why do the ultrafire come in different colours? does it mean anything if the battery is blue or gold and black or red and black? I am a bit confused by all the different capacities and colours