Straight barbells are straight rods with balls threaded onto each end. A circular barbell is a heavier barbell curved into approximately a three-quarter circle. A fourth variation is called a slave, banger or captive barbell and has a CBR attached to one or both ends of the barbell. Barbells in complex shapes and with charms instead of balls are also common. Labret studs and L-shaped fishtail labrets are used in cheek, lip and labret piercings.
Labret studs are barbells that have a small thin disc soldered in place of the ball on one end.
Fishtail labrets are intended to fit into the indentation below the gum line and are usually slightly flexible to permit adjustment of the mouth bar. Nostril screws are shorter versions of labrets used for non-septum nasal piercings. Jewelry material varies a lot. Those materials most frequently encountered are those that are safe for new piercings. 14kt and 18kt yellow and nickel-free white gold are also used but most piercers do not use 14kt in new piercings.