Description: Companion Flange, sometimes referred to as a hub, is a flange that corresponds to another flange. It has bolt holes that align with another flange is a trait of this type of flange. Usually a companion flange features a Raised Face (RF) or Ring Joint (RTJ), with a threaded outlet. Also called a Threaded Flange by some people. Specifications: Size: 1-13/16" - 26-3/4" Working Pressure: 2000PSI, 3000PSI, 5000PSI, 10000PSI, 15000PSI, 20000 PSI Standard Material: AISI 4130(forged) 75K/ 410 Stainless Steel Face Type: RTJ, FF, RF Connection: Bolted or Studded Surface Treatment: Anti-Rust Oil, Transparent/Yellow/Black Anti-Rust Paint, Zinc, Hot Dipped Galvanized. Temp Class: K-V Material Class: BB, CC, DD, EE, FF PSL Rating: PSL1, PSL2, PSL3 PR Rating: PR1, PR2