CaribSea Rock Lock Reef Cement. Rock Lock is an incredible reef cement that sets in just about two minutes. Perfect for attaching corals or creating rock sculpture, and can be used in or out of water. Create dramatic rock sculptures instantly Easily attach corals to existing structures Can be used underwater or out of water Sets in 2 minutes Safe for use in marine and reef aquariums Easily cement rocks to created dramatic structures or attach corals to your existing reef scape. CaribSea Rock Lock is a 2 minute fast-setting reef cement that can be used either in or out of water to create bonds in mere minutes. Safe for marine tanks, fish, corals, and other invertebrates. Available Size: 500ml