Butt-end aluminum bands are issued to banders unless another type of band is specifically requested. These are available in sizes 0A through 9C.
Pre-opened bands were formerly available in sizes 1A to 7B (except 3B and 4A) and are the same as the closed bands, but are partially opened and strung numerically on plastic tubing. These bands are of particular value in large-scale banding operations in which time is a factor. The bands can be used without further opening. In recent years some pre-opened bands were ordered in sizes 0A, 1C, and 1B.
Pre-opened bands are more expensive than the standard butt-end bands and have been largely discontinued; limited quantities are still available.