The Scarpa Phantom Ultra is the lightest boot in Scarpa's next generation Phantom series. The upper has been made with a combination of materials designed to save weight yet provide enough insulation & weather protection for Scottish winter climbing & summer alpinism. It also has a new Pentax Speed sole unit that blends specialist materials with a Vibram Mulaz outsole to create an ultra light, comfortable, tough & functional sole. Glossary:VIBRAM: High quality rubber soles that are renowned for durability & stability on all surfaces & in any environment.