New Balance Men's RX506R Track Shoe 100% Mesh and synthetic Rubber sole ACTEVA LITE is 24% lighter than standard midsole foam with Dupont Elvaloy and Dupont Engage for optimal compression set properties 3/4 ROCK STOP plate utilizes a flexible protective layer that protects feet from rocks and shock, minimizing pressure, and dispersing shock energy 4 spike configuration NLOCK is an integrated lacing and webbing system that provides optimal fit, support and security Rubber lug