Deck-O-Seal® 470203196 oz White Two Part Gun Grade Joint Sealant Kit 4 per Case. DECK-O-SEAL GUN GRADE is a two-component, non-sag, non-flowing, polysulfide-based sealing compound. It is a non-staining sealant that cures to a firm, flexible, tear resistant rubber. DECK-O-SEAL GUN GRADE is highly resilient and has excellent recovery characteristics, even after extended periods of compression or elongation. It has outstanding resistance to most chemicals, to all weather conditions, aging and shrinkage.