Straight barbells can be of different size and shape and can be used for almost any type of piercing. There are innumerable varieties of these, so anyone can find one that suits him or her. The different beads allow for self-expression whereas the size, shape and type of screwing depend on the piercing you have. There are barbells with one bead fixed or those with both unscrewable, also you can choose between externally and internally threaded barbells. The latter are less likely to cause damage and irritation, especially at the time of piercing and therefore are getting more and more popular.