Spring Hose Clamps are commonly used by the OEM in low pressure applications such as PCV (positive crankcase ventilation) and coolant hoses. They have a constant-tension spring-action band that allows the clamp to automatically expand and contract with hose temperature fluctuates. They do not dig in and permanently damage the hose like worm-drive clamps. The Spring Hose Clamps are made from steel and are zinc plated to resist corrosion.