Rescue Tethers are an incredibly useful add on for rescue vests.  There are a number of uses for this attachment:

• Towing boats
• Towing a lines for line crossings
• Towing paddles (often with an oversized paddle carabiner)
• Dragging gear when it may be unsafe to carry or to save trips
• Retaining your boat in mid-stream rescues

When using this device, think about whether you have adequate tension to effect a quick release and adjust the threading of your quick release accordingly.  Also, when towing a boat - consider what's downstream.  Ask yourself, do you feel comfortavble running that rapid with a several hundred pound object holding you back? 

When finished using the tether, can you quickly stow to avoid having it get in your way or accidentally clipping into something. 

Another choice that causes endlesss debate: Bungee or static fixed line.  Frankly, this is really a matter of choice.  The bungee style is faster to restow as it coils up automatically. The downside is the spring action when towing which is why I prefer a static line.

I use mine frequently when leading trips with paddlers "Stepping it Up".  The Rescue ATether is a great time saver.