Hollow Brick Winged Nylon Expansion Anchor Barb Lock Sleeve Plug for Cavity Clay Block Aerated Concrete Wall Fixing Product Description The Hollow Brick Winged Nylon Expansion Anchor is specifically designed for hollow clay blocks, cavity bricks, and aerated concrete substrates prevalent in European and Asian residential construction. Standard expansion anchors often fail in these materials because the anchor either spins freely in the hollow cavity or crushes the thin,