Dogs read body language better than they read English. They are hardwired to look at your posture. By downloading a hand signals PDF, you are switching to their native language.
Your voice doesn’t carry well across a windy park or a busy street. A visual signal cuts through the chaos. A simple "down" hand motion from 50 yards away can stop your dog from chasing a squirrel into a dangerous intersection.
You might just be amazed when your dog sits before you even open your mouth.