This mast-mounted large Aerovane is specially designed for use on dinghies, sport boats, and keelboats up to 28ft. With its built-in counterweight, it accurately indicates apparent wind angle and prevents flapping in strong winds. It also features an adjustable tacking tab system for clear display of apparent wind angles, particularly useful for boats with a spinnaker. The large size allows for easy reading without creating drag, and its pad-printed white underside provides good contrast against the black plastic for better visibility from the deck. For assembly, firmly push the Aerovane onto the rod until you hear a click, and it can be removed with a strong pull. To attach to the mast, use the supplied A4066 burgee clip or A.172 mast crane adaptor (sold separately). The adaptor screws into the tapped hole on the mast crane and secures the Aerovane with a small grub screw.