FLAT stainless steel 5" machined v-band weld flange. Mates to industry standard 5" (use 5" tube) v-band flanges and use 5" standard v-band clamp (actual outer ring is 5.25") to join two of these flanges. Also mates to most standard turbine housings with 5" v-band (5.25" outer ring) flange such as the Garrett v-band GT55/GTX55 housings.
