Flange Kits Bolt Hole Size 1.75 in Compatible Pipe Size 3/4 in Compatible with Brand Armstrong Compatible with Series Astro 2 Design Envelope Compass Compatible with Series Family Astro 2 Design Envelope Compass Flange to Pipe Connection Type FNPT For Use With Potable Systems Yes Flange Type Standard Number of Mounting Holes 2 Compatible with Manufacturer Model Number Astro Astro 210SS Astro 280SS Astro 286SS Compass R 20-75 Compatible with Pump Type In-Line Circulating Pumps