Click to learn more about the features and benefits of the KLOGS Cobra Insole. PLEASE USE THE SIZING BELOW FOR THE DRX Cobra Footbeds. Womens: Small 6-9, Medium 10-13 Mens: Small 5-8. Medium 8-12 Developed by a podiatric surgeon, the DRX Cobra Footbeds will bring much needed relief! Made with Ultron single density polyurethane. Helps alleviate shoe-related foot pain. Functioning orthotic for use in shoes with no arch support. Soft microfiber cover. Imported.