DUO combines the power of air pressure and the gentleness of vacuum to give you the fastest most powerful self contained supplemental brake ever. Duo uses the power and speed of air pressure to activate your towed vehicle brake pedal while creating vacuum for the power brake system.

These two features combine to create the only progressive and proportionate vacuum assisted system with total control. Duo requires BOTH deceleration AND coach brake lights to apply the towed vehicle brakes. By combining two separate signals the need for complicated electronics is eliminated, which provides you a more reliable long lasting system. In addition, DUO is the pioneer in user friendly operation; "Just Turn it on...and Tow."

This simple technology was first introduced in 2003. Tried and true, DUO does not have to be taken in and out for normal operation of the towed vehicle. Unhook the car and drive off, that's all. No box, no wires, in fact, no physical connection to the motorhome at all.

• Patent-pending air cylinder applies your towed vehicle’s power-assisted brakes AND automatically applies proportionate and progressive brake effort. Only 10 pounds of force on your brake pedal in normal braking.
• "Panic Stop Braking" - only Demco brings you additional stopping effort in a panic... up to three times the normal effort.
• Coach notification of brakes applied with every unit.
• The Stay-IN-Play DUO creates vacuum to provide totally reliable and consistent brake application.
• Two signals are required to activate the Stay-IN-Play DUO system. The coach brake must be applied, AND there must be sufficient G-force.Stay-In-Play Duo should not activate while the coach or towed vehicle is not moving.No unwanted or unnecessary brake activations on grades or over bumps. And best of all, it is all automatic.
• "Zero" set up for towing - the Stay-IN-Play DUO is always ready to tow.
• Simple installation mounts the small operating unit under the hood of the towed vehicle so you never know it is even installed.
• The air cylinder is so small it fits in the palm of your hand. No other system offers this much control and this much power all combined with a simple install.
• On/off operation means you are tow ready in less time.