Stone MSWS Pro Four is the official sock Lurbel has developed in collaboration with the Merrell Skyrunner World Series for the 2026 season. A special edition built for the demands of the world skyrunning circuit, where terrain is technical, intensity is high and your feet need consistent protection. Two colourways, one purpose: deliver the same performance when the distance, elevation and effort get serious.

Its construction is made for mountain running at race pace. A seamless perimeter helps minimise friction points, while an asymmetric left/right design improves the natural fit on each foot. Self-ventilating zones are placed in high-sweat areas to speed moisture release, and a double-density cuff reinforces hold without turning it into pressure—keeping the sock stable on climbs, descents and fast transitions.

At the core is Bmax Tetra technology, created to tackle the three main triggers behind blisters and rubbing: overheating, moisture and friction. Regenactiv® acts directly on the skin to help reduce irritation and heat build-up caused by rubbing, while a multi-channel structure moves sweat outward quickly to maintain a drier environment under high intensity. The result is long-wear comfort when the race stretches on and your feet start asking questions.

Underfoot, the AWC (Air Waves Comfort) plantar structure raises mountain performance with an optimised cushioning system that combines relief waves and integrated ventilation channels. The waves deliver a soft, responsive cushioning feel that absorbs impact on uneven terrain without adding weight, while the channels support fast moisture dissipation to help keep your feet drier and more stable in every climb.

Developed and locally produced in Ontinyent (València).