Sleeve anchors are a type of masonry fixing that are commonly used to attach objects to concrete, brick, or block walls. They are a popular choice for securing heavy items such as shelves, brackets, and safety barriers. The sleeve anchor is made up of a cylindrical metal sleeve, usually made of steel, that is threaded on the inside. The sleeve is inserted into a pre-drilled hole in the masonry and a bolt is then threaded into the sleeve, expanding it and creating a tight grip against the sides of the hole. Sleeve anchors come in a variety of sizes and lengths, and can be made from materials such as zinc-plated steel or stainless steel to provide corrosion resistance. They are typically installed using a hammer drill to create the hole and a torque wrench to tighten the bolt to the manufacturer's specifications. When choosing a sleeve anchor, it's important to consider the weight of the object being attached and the type of masonry it will be installed in. Consult the manufacturer's guidelines to determine the appropriate size and length of sleeve anchor for your specific application.