Made of hardened spring steel plated to resist rust and corrosion, these fasteners use spring tension to hold screens or storm windows firmly in place. They stop window rattling because they hold tight, and help save energy by keeping storm windows held snugly in place, reducing heat loss. Two types are available – regular Ludwig Fasteners are made to hold wood framed screens and storm windows; deep fit fasteners are designed to compensate for the difference in the thickness of wood window frames and thin aluminum screen or storm window frames. Use them on the side and top of windows, as a window safety lock, or for combination doors – and many other applications. Packed 1 gross (144) fasteners per box with screws.