While our particle counters can measure between 0.3 or 0.5um and 25um the selectable channels can only go up to 10um. Meaning you can only select channels between 0.3/0.5um and 10um - the 10um bucket counts all particles 10-25um.
If you are looking to measure 1um, 5um, 10um, 15um, 20um, 25um on separate channels and this is not possible with our standard units. There is an option for that.