... TE0503, is reliable and easy-to-use machine. It's handheld, ergonomically designed and lightweight. The Model TE0503 counts airborne particles ... counts, counts/cbm, counts/cu.ft.Sampling modes manual repeated, auto for UCL calculation for all 6 channelsKey internal software features ... recharging external chargerOperating temperature 10 - 35°COperating humidity 0-85% handheld Particle Counter