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.
The daith piercing is a small ring that pierces the inner cartilage of either ear, running through a pressure point, which for some will relive migraine pain. It is a relatively new procedure, mainly preformed at tattoo and piercing shops with not many statistics to back it up yet.