What are ten penny nails?

Ten penny nails, often referred to as "10d nails," are a type of fastener used in construction and woodworking. The "penny" designation comes from an old British system where the number indicates the length of the nail; a 10 penny nail is typically 3 inches long. They are commonly used for framing, sheathing, and other structural applications due to their strength and length. In terms of gauge, ten penny nails usually have a diameter of about 0.135 inches.