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.
A daith piercing is a type of ear piercing where an earring goes through a piece of cartilage in the outer ear. Specifically, the earring goes through the firm piece of cartilage called the helix just above your ear canal. Daith piercings are commonly small, looped earrings, but some people gets studs. The procedure itself may be painful.