The standard for a currency strap according to the American Bankers Association is 100 bills of the same denomination, with the exception of $1 bills, which can also be arranged into straps of 25, 50, 200, or 250. The Federal Reserve use bundles of ten identically-denominated straps.
The ABA Standard employs color-coded bands for straps to improve counting efficiency. Each colour corresponds to a distinct denomination and, in the case of $1 bills, a distinct sum.
The Federal Reserve packaging requirements prohibit the use of paperclips, rubber bands, and sub-straps, as well as limiting the number of bands that may be wrapped around the straps. Every 10 straps of the same denomination are bundled together with elastic bands or zip ties.
