The combination of webbing strap and cam action buckle that is used to secure the cylinder to a buoyancy compensator or backplate is known as a cam band or cam strap. They are a type of tank band, which includes the stainless steel straps used to hold twin cylinder sets together. They generally rely on an over-centre lever action to provide tensioning and locking, which may be modified by length adjustment slots and secondary security fastening such as velcro to hold the free end in place. Most cam buckles for scuba are injection moulded plastic, but some are stainless steel. Many recreational scuba harnesses rely on a single cam band to hold the cylinder to the backplate. Other models provide two cam bands for security. A cam band can also be used on a sling or sidemount scuba set to attach the lower clip to the cylinder.