The Series 4 cells deliver 40% more capacity than typical sport packs (3000mAh), and that means longer run times?but that?s just the start! Greater capacity also means the Series 4 packs maintain peak voltage levels under load, so that punchy, just-charged feel lasts longer than ever.Power Cell Series 4 packs are optimized for free-flowing power and maximum punch with premium quality, low-resistance cells; flexible, silicone-jacketed 12-gauge wire; heavy-duty welded tabs; and Traxxas? high-output, gold plated, high-current connectors. Precision assembly with attractive, individually wrapped cells and clear overwrap complete the package.Traxxas Series 4 Power Cell battery packs provide the most power and runtime possible with NiMH cells. Upgrading from a 6-cell pack to the powerful Traxxas 7-cell 8.4V pack is the most cost-effective way to instantly increase top speed by 5mph or more with no other modifications. The 7-cell hump pack fits in all Traxxas models except E-Maxx and E-Revo, which require a stick pack configuration.