I am looking to start building my own battery packs. I bought the Deans battery Jigg, Pro 3 connectors, Pigtails and Ultra plugs. (All on the suggestion of other RC racers). Now comes the difficult part. Selecting batteries. I am currently running Pre-made 3000 packs, made by Venom. But everyone says I should get "Matched Batteries"??? Since I am new to all this, what the heck does Matched mean?......lol. Does anyone have a suggestion for a website and or what type of batteries to get? I am running a XXX-T, B4 and a RC10-T3 at my track on alternating weekends, and we race Three 5 min. heat and One 10 min. Main if that helps. Thanks ahead of time for any input/help.[?] Frank.