The image shows an RT-FM4B fuel dispenser flow meter, a type of positive displacement meter. It uses advanced technology and can be widely used for different fuel dispensers. Key advantages include high flow, long working life, high accuracy, and a firm structure. It is made from aluminum alloy low-pressure casting and is used for gasoline, diesel, and kerosene. The primary function is to accurately measure the volume of oil output. The basic relative error is approximately \(\pm 0.2\%\)