Abstract: A composition comprising: a plurality of identical first synthetic nucleotide oligomers; and a plurality of identical second synthetic nucleotide oligomers which are different to the first synthetic nucleotide oligomers, wherein each of the first synthetic nucleotide oligomers comprises a first primer binding sequence of bases, a first identifier sequence of three to seven bases in length, and a second primer binding sequence of bases, the first identifier sequence being disposed between the first and second primer binding sequences, wherein each of the second synthetic nucleotide oligomers comprises a third primer binding sequence of bases, a second identifier sequence of three to seven bases in length, and a fourth primer binding sequence of bases, the second identifier sequence being disposed between the third and fourth primer binding sequences, and wherein the first identifier sequence is different to the second identifier sequence.

Abstract: A security system comprising: a controller; and a plurality of dispensing devices, wherein the controller is configured to receive signals from a plurality of remote detectors and transmit signals to the plurality of dispensing devices, the controller being adapted to determine which of the plurality of detectors has transmitted a signal and transmit a signal to a selected one or more dispensing devices to dispense a fluid based on said determination, wherein each dispensing device is configured to receive signals from the controller and dispense fluid when a signal is received.