The cost of the extender cap isn't that much and you will get the original cap with it as well although in your case you will be ordering one of the collectible end caps ( I wish they had them for the extender caps ) . I would also order the 510 to ego adaptor now to save on shipping because chances are you are going to want it later . I use 18650 1600mah AW IMR batteries and I use two in a night . I have 4 batteries in rotation . The 2500mah batteries do sound interesting possible when the batteries I have start to degrade and I need to get more I might consider them but I am satisfied with what I have now .
