Capsicum Oleoresin is prepared by extracting the crushed capsicum (Capsicum Annum Linn) with volatile solvents by percolation method. It contains the pungent principles, capsicin not less that 8 percent. It also contains the red colouring matter called Capsanthin. This product is a powerful irritant and a carminative, which is also used as a counter irritant in lumbago and neuralgia. It can also be used to treat stomach ache that involves poorly functioning stomach muscles and as an antibacterial agents. Extraction of oleoresin capsicum from peppers involves finely ground capsicum, from which capsaicin is extracted in an organic solvent such as ethanol. The solvent is then evaporated, and the remaining wax like resin is the oleoresin capsicum. An emulsifier such as propylene glycol is used to suspend the OC in water, and pressurized to make it aerosol in pepper spray. The high performance liquid chromatography (HPLC) method is used to measure the amount of capsaicin within pepper sprays. Scoville Heat Units (SHU) are used to measure the concentration or "heat" of pepper spray. A synthetic analogue of capsaicin, pelargonic acid vanillylamide (desmethyldihydrocapsaicin), is used in another version of pepper spray known as PAVA spray which is used in the United Kingdom. Another synthetic counterpart of pepper spray, pelargonic acid morpholide, was developed and is widely used in Russia. Its effectiveness compared to natural pepper spray is unclear. Pepper spray typically comes in canisters, which are often small enough to be carried or concealed in a pocket or purse. Pepper spray can also be bought concealed in items such as rings. There are also pepper spray projectiles available, which can be fired from a paintball gun. It has been used for years against demonstrators. Derived from chilli peppers, oleoresin capsicum is the active ingredient in pepper spray and in some topical pain relievers.