A mount to secure headset control module.  Plastic  is UV resistant.  For type, "Flange" is the one with screw locators on each side and "No Lower Flange" is recommended to be mounted with 3M Dual Lock.   It is a smooth fit but not too tight in order to preserve the cloth material.   The price is for one part.  If you need both pilot and copilot side then order two.