Measuring a bicycle chain's pitch can be used to identify chain wear and flag the need for a replacement chain and/or cogs and chainrings. Bicycle Chains: Length, Width, What's Best to Buy etc.
An industrial, or scaffold, piercing is made up of two holes that are connected by a single piece of jewelry (usually a long barbell). An industrial piercing is commonly made through the cartilage on the upper ear, with one hole close to the head and the other further down on the outer rim. Two or more industrials on one ear is sometimes referred to as an ear cage.
An industrial piercing is many times referred to as a bar and is usually done in the ear lobe. Unlike a normal ear piercing, this kind of piercing uses a scaffolding technique. Also known as a scaffold or construction piercing, an industrial piercing will have two holes that are connected by a piece of jewelry.