These metering pumps are ideal for low flow, low pressure metering applications where a fixed flow rate is required. Like the Mini Bellows Metering Pump line, the Pocket Bellows metering pumps are constructed entirely of plastic and uses GRI’s bellows technology to provide an accurate chemically-resistant metering pump with a long life, at an economical price. The only difference is the Pocket Bellows line utilizes a fixed crank mechanism.