Spenco PolySorb Cross Trainer Insoles are for all sport or athletic activity – aerobics, court sports, running, weight training, racquet sports and walking. The Spenco PolySorb Cross Trainer features special cushioning in both the heel strike zone and the forefoot area for outstanding performance. This Insole helps turn any athletic shoe into a cross training shoe. For aerobics, court sports, running, weight training, racquet sports, walking, etc… Special cushioning in both the heel strike zone and forefoot area for outstanding performance Helps turn any athletic shoe into a cross-training shoe