For those looking to achieve their personal goals, the Liberty ISO 2 lets you boldly chase after them. This running shoe sports a light and springy feel with a touch of stealth stability to keep you comfortable as the miles rack up. ISOFIBER replaces an external support frame for increased midfoot/heel structure and security. Upgraded mesh from engineered to ISOKNIT construction. More guidance added to the TRI-FLEX outsole. Heel: 4mm. Weight: 9.9oz.