Wristpack

The wristpack or wrist pack, is a fanny pack worn on the wrist which was popular in the early 1980s. The item was designed for runners and cyclists to as a wrist wallet for their keys and money while performing physical activities. The wristpack became popular amongst children and teenagers and were available in an array of colors and designs. A southern California company named IMUNE claims they were the first makers of the wristpack in 1983, though it is hard to pinpoint its first reference in popular culture.

...
Wikipedia