These MasonMate Hex Loose Bolt Sleeve Anchors have the following specifications: Size: M16 x 75mm. Max. Fixture Thickness: 20mm. Min Hole Depth: 55mm. Qty Per Box: 25. The MasonMate Hex Loose Bolt Sleeve Anchors are for use in most types of masonry or concrete. Zinc Plated for increased durability. M16 x 75mm (25)