The CPC Battery allows us to obtain complementary information on the aerosol size distribution in the sub 10-nm size range. It consists of several CPCs with different lower cut-off (threshold) diameters, which measure the particle number concentration in parallel. The use of the CPC battery adds some extra bins to the size distribution measurement provided by the nano-SMPS, with a very high time resolution, allowing for more precise growth rate calculations. Moreover, the use of both butanol and water CPCs in the battery will permit us to obtain some additional information about the hygroscopicity of small particles.