O-Ring Aluminum RetroDrain Is designed as a retrofit drain option for installation into existing leader pipes with a smaller or larger I.D. features an aluminum body with an extra large flange for positive attachment of the roof flashing membrane and four rubber O-rings to make a watertight seal. It's available with either a U-Flow cast aluminum strainer dome and cast aluminum clamping ring, cast aluminum SuperDome, plastic dome or a RAC aluminum strainer dome.