Flange Kits, Bolt Hole Size 1.75 in, Compatible Pipe Size 1 in, Compatible with Brand Armstrong, Compatible with Series Astro 2, E.2, S&H, Compatible with Series Family Astro 2, E.2, S&H, Flange to Pipe Connection Type FNPT, For Use With Potable Systems No, Flange Type Standard, Number of Mounting Holes 2, For Use with Mfr. Model Number Astro 290SS, E10.2HT, E11.2HT, E13.2HT, E19.2HT, E21.2HT, E22.2HT, E23.2HT, E24.2HT, H-32, Compatible with Pump Type In-Line Circulating Pumps