Designs include both diaphragm (hydraulic or mechanical), reciprocating piston plunger, stepper motor plus worm and wheel spring return gearboxes. Materials ranging from PVC to PVDF with complementary range of elastomers. Flow capacities are available as low as 0.1millitres per hour up to a maximum flow rate of 1000 litres per hour. Current maximum pressure rating is 100 Bar. Control features include manual length/frequency on/off; milliamp; pulse; pH; redox (ORP); conductivity; timer; batch; ppm; MODBUS etc.