Spenco Polysorb Cross TrainerKeep your feet in fighting form with support and cushioned protection of the Spenco® PolySorb Cross Trainer insole. Ideal for running, walking, and training. Silpure antimicrobial top cloth reduces friction and heat build up with it's four-way stretch nylon construction, preventing blisters and calluses. SpenCore™ heel-to-toe cushioning provides full coverage protection. SBR rubber cushions the forefoot and adds extra protection against shock abrasion. Spencore™ heel-strike pad offers focused cushioned protection. Lightweight, contoured POLYSORB™ polyurethane foam bonds to closed-cell nitrogen-injected Spenco material, cradling the heel and support of the arch.