This unit is designed to slide over the end of the 2” O.D. tube protruding from a cabin heat box that extends through the firewall. The short end of this unit is expanded to 2” I.D. One stainless steel clamp is furnished with the unit. If you use scat tube, the 90° angle allows you to run the scat tube parallel to the firewall and away from undesirable areas (brake pedals, etc.) Constructed of seamless 6061T4 .028 wall tube. Weight: 1.4 oz.