The bands that hug the quarterback’s non-throwing wrist and forearm contain dozens of plays with corresponding numbers or codes. They are often as much a benefit to the play-caller as to the QB because he can just call out a simple number rather than the entire play sequence with all its protections, checks and other nuances.

To help ease this burden, quarterbacks often sport these wristbands that carry a “portable playbook.” These wristbands are commonly refered as wrist coaches.