Carriage Bolts help you board-up windows in a hurry Carriage bolts are not "locks" in the usual sense, but they can be used to secure a property by helping you board-up broken or missing windows, or to protect windows with plywood before an approaching storm. Using carriage bolts to board-up windows following (or prior to) weather damage or vandalism is a fast and easy way to secure your property when time is running short. Each zinc-plated steel carriage bolt is threaded for at least 3/4 of the length of the bolt. Choose from three different lengths of 3/8" carriage bolts: 10", 12" or 14" lengths. Sold as a package of 12 carriage bolts, each with a flat washer and nut.