Rambo’s frame integrated batteries allow the battery sit lower on the bike frame than a standard battery. By placing it lower on the frame it helps keep the weight lower and gives the bike a faster, more responsive ride. Our integrated battery packs use the very best lithium ion batteries. Our integrated batteries are designed to be universal and allow you to upgrade to a whopping 21-amp hour battery! The 21-amp hour battery can give you a max distance of 60 miles! Not all batteries are equal. In fact, not even close. Many e-bikes that are advertised on the market today at a certain amp hour fall very short. Real life tests show Rambo outperforms again and again! Don’t be fooled for less than the best!