Superior Mondo rubber wood flooring is inherently stable, with graded lumber on top and a graded lumber sub-floor below, providing total uniformity and eliminating dead spots. The hardwood is exposed beneath, allowing it to be dried, and the 1'x6" sub-floor is able to expand, contract and move effortlessly with the maple playing surface. Air-Flow is inexpensive assurance to the district that their floor is being continuously monitored and controlled. With Superior, the gym flooring will last the life of the hardwood, not the life of the plywood.