Seal For Fleck Metal By Pass Valves. (Replaces FL11726) Older bypasses were Brass, or Nickel Plated Brass. Newer Bypasses are made of Stainless Steel. This Seal will work on either the 3/4" or 1" bypass valves, and on both the old and new models. A Leaking bypass can be easily fixed by replacing this Seal Gasket, which should take about 10 minutes. Simply remove the four bolts on top and four bolts on the bottom of the Bypass, that are holding this seal in place. .