Carriage bolts commonly have a smooth, domed head with a square section underneath that is pulled into material to prevent spinning during installation. This allows the bolt to self-lock when it is installed through a square hole in metal straps, or a round hole in most woods. It can be installed using a spanner or a wrench. Depending on your application, we supply a wide array of materials and grades, such as hot dipped galvanized carriage bolts, Grade-5 and Grade-8 carriage bolts for greater load carrying capacity, or 316 stainless steel carriage bolts for greater corrosion resistance. As always, we are always here to help, so if you don’t see the exact product or size you need, please contact us for assistance.