Compact Tube 400 Slim, integrated, compact and delivering 400 watt hours at a weight of only around 2 kilograms, it's a real energy champion: The CompactTube 400 with innovative battery cell technology offers the highest energy density of all Bosch eBike batteries. This makes the extra-lightweight battery the ideal choice for sporty, light eMTBs, minimalist eGravel bikes or design-oriented eUrban bikes - in short, for anyone who loves the sleek appearance of conventional bikes but doesn't want to do without electric support