Simple design that works incredibly well. If youre shopping for a window stop, there is a good chance you are replacing one that has worn out. This simple Perko design has been used for decades and there is an excellent chance the screw holes are the same. Designed to be installed on the sill, this stop provides a hinged arm that flips in place to secure sliding windows open in heavy chop or rough seas or closed for security while you are away from your boat. The stop features a Black polymer cover to protect the glass from direct metal contact that can result in chipping. For a quick replacement for a worn out stop or to install a proven design able of securing sliding windows, trust a Perko sliding window stop to do the job. Key Features Tried and true stop for sliding windows Designed to be installed on window sill to hold open or closed sliding windows Chrome-plated zinc construction for corrosion resistance Black polymer cover to protect glass from direct metal contact Counter-sunk mounting holes for flat or oval head screws