An endpin is an adjustable rod on the end of a cello or upright bass that holds the instrument upright while it is being played. Cello endpins vary according by their material, width and length. They can also be either straight or bent.
A variety of materials can be used for cello endpins. The earliest endpins were made of wood, but more durable metal options began replacing wooden ones in the early 20th century. Going into the 21st century, tempered steel remained the most popular choice for cello endpins. Some cellists prefer fiberglass or carbon fiber endpins, however, which are lighter weight and absorb less of the instrument's vibration. Regardless of the material of the endpin, it is usually capped with a rubber stopper that keeps its sharp end from damaging flooring.
Cello endpins generally come in two widths: 0.32 inches (8 mm) or 0.39 inches (10 mm). Some cello experts recommend the 8 mm width since it is lighter, but others think that a 10 mm pin is sturdier and more secure. Either width will fit into standard fittings. The fittings, however, must be the appropriate width for the endpin opening of the particular instrument: 0.93 inches (23.5 mm), 1 inch (25.5 mm) or 1.1 inches (27.5 mm).
Styles for the length of cello endpins have varied over the years. Early endpins were only a few inches long, whereas contemporary versions can typically be extended up to 20 inches (45 cm) below the bottom of the instrument. A longer endpin results in the musician holding the instrument at a less upright angle, which some people find results in a more natural playing position.
To make the instrument's angle even closer to horizontal, some players favor a bent endpin. This is one of the more recent developments in cello equipment and had not gained widespread popularity as of the early 21st century. While some players feel that they have greater control over their instrument's tone quality with a bent endpin, others still prefer the more upright positioning of the instrument. Some cellists also think that a bent endpin does not support the cello's weight as well as a straight endpin, which may result in damage to the instrument.