1 flange (with 81mm centering ring) and 1 clamp to mate to "GT style 3" v-band discharge on "GT" style turbine housing where the flange has a 3.55" (90mm) OD.. Heavy Duty Stainless Steel V-Band Clamp and special Stainless 3" flange with protruded lip for GT V-band housings with lip on V-band. Also same (slightly smaller) outer diameter as GT V-band housing outer diameter. Only use this flange if you have a mating flange or housing that has a recessed ID for the protrusion on this flange to sit into.