Press-in hooks are used in wall construction to connect reinforcing steel bars. They are typically made of steel and have a hook shape on one end. The other end is inserted into a hole in the wall and then the hook is bent over to secure the bar in place. This creates a strong and rigid connection that helps to reinforce the wall and prevent it from collapsing. Press-in hooks are a quick and easy way to connect reinforcing bars and they are often used in high-rise buildings and other structures where strength and durability are important.