How much does this cost to the nearest dollar?

Crossfire Dual Tire Pressure Equalization System, 95 PSI, one per pkg.
America's Leading Dual Tire Pressure Equalization System Saves You Time and Money. Dual tires have a set of problems all their own. In motion, the inner tire's temperature increases due to in-board brakes and poor air circulation. This causes increased air pressure, which expands the inner tire's diameter. As a result, the dual tire configuration is now distorted- the diameters are unequal. Crossfire is a pressure equalizing and monitoring valve that is mounted between dual tires. It bolts easily to the lug, hub cap, or drive axle end. Properly mounted, air freely flows from one tire to the other, maintaining equal tire pressure and load distribution.The Crossfire Dual Tire Pressure Equalization system Maximizes tire life

Price is $71.00
Price: $71.3