The units are graded according to four variations in operating frequency. Each type can be identified by the colour coding on the sensor label and carton. For reliable operation it is essential that units of the same colour code do not occupy adjacent positions in open-plan areas or in adjacent rooms. (See installation instructions for MS2421P, MS2421A, MLS2421D or MLS2421A for an illustration of how to position the colours.)
An order for a number of Gold Series sensors would be sent out with an appropriate mix of colours. If replacing an existing sensor, one of the same colour would probably need to be ordered using the suffixes B, Y, G or R for blue, yellow, green or red.