The stick is used to elongate your arm. It's made of a strong glass fiber stick, with a rubber grip on one end and a durable nylon loop on the other end.
Why use a stick instead of a whip?
A whip is flexible, which means you'll have difficulties controlling the movement of the tip. It will either feel too whimpy to the horse, or it 'snaps' and accidentally hurts him. A stick is much more suitable for ground work, because the sturdy, unbendable material allows you to transfer the feel from your hands to your horse. You can pet, push or tap, with the same feel as touching your horse with your hands.