The reservoir cap is an integral part of the onboard diagnostic and emission control system. It prevents fuel leakage from the filler neck, a significant source of hydrocarbon emissions, and plays an important role in preventing fuel flow.

Studies have shown that a defective or missing reservoir cap can allow up to 114 liters of fuel to evaporate into the atmosphere each year.

Farma's reservoir caps are designed and manufactured to prevent fuel loss mainly through evaporation. The caps are designed to lock to prevent fuel theft and vandalism. Opening and closing are easy.