Write directly on tags with pencil, pen or permanent marker to keep track of which keys are which. For use with rack-style cabinets. Sturdy plastic tags with durable nickel-plated metal snap hooks hold one or more keys and make it easy to switch keys out.Write directly on tags with pencil, pen or permanent marker to keep track of which keys are which. For use with rack-style cabinets. Sturdy plastic tags with nickel-plated snap hooks hold one or more keys.