Profile: GRIMM Technologies, Inc. manufactures real time portable and stationary aerosol ultrafine particle counters, spectrometers, SMPS +C systems for environmental, laboratory, IAQ & field applications. Our products include scanning mobility particle sizer with faraday cup electrometer, model 55-U universal DMA, model 5.402, 5.403 condensation particle counters, model 180 environmental monitoring station, model 565 WRAS wide range aerosol spectrometer and model 1.109 31 channel real time aerosol spectrometer. Our model 55-U universal DMA is an interchangeable DMA. and the kit allows the user to work with either a 5-340nm or 10-1100nm DMA. This capability is achieved by the ability to interchange the cylinder and inner rod of the DMA. It has a unique universal adapter for inner (center) and outer cylindrical electrodes. With this design of the U-DMA, three different lengths of the middle parts (electrodes) can be attached or exchanged to cover 3 different measurement ranges (L-DMA/M-DMA/Nano- respectively S-DMA).