Boot struts, also known as tailgate or trunk struts, are gas-filled hydraulic cylinders designed to support and smoothly lift or lower the boot (trunk) or tailgate of a vehicle. They provide controlled motion and hold the boot open securely, preventing it from slamming shut. Over time, boot struts can lose pressure or fail due to wear and temperature changes, resulting in a heavy or unsteady boot lid. Replacing worn boot struts restores smooth, safe operation and ease of access to the trunk area.