SPECIAL ORDER ITEM. Review Returns Policy before purchase. The 3 in red rubber full-face flange gasket kit is widely used for plumbing flange connections. The gasket is a continuous, full-surface seal that helps prevent leaks where two flanged pipes or fittings meet. It comes with appropriately sized hex bolts and heavy hex nuts sized for a 5/8 in x 3 in bolt pattern, and the rubber gasket material is 1/16 in thick for reliable compression and sealing under tightening.