151 The Original Gorilla Filler, 750ml Expanding Foam, Seals & Fills, Squeezes into Gaps, Suitable for Filling & Sealing Gaps & Cavities. 151 Gorilla Filler is the ideal solution to large cracks and holes in stone, wood, brick and metal. It expands on contact to fill any shaped gap and hardens to form an airtight weatherproof seal. Can be cut, sawn, painted or sanded.