To fit 4" diameter (inside dimension) of existing PVC or cast iron pipe - Your new 26. Ga. Stainless Steel custom plumbing vent to be 5-1/2" (inside dimension) in diameter to allow for pipe wall thickness and some space for field variations. Will fit the 4" PVC or cast iron pipe with 1/4" to 3/8" wall thickness. All connections and joints soldered with 50/50 solder and prepped with flux. Pure copper company name tag to be 1/4" tall by 3" wide "Ray Bros Inc." Three day lead time to fabricate, before shipping.