Mixing the comfort of Polyester with a new age fibre, Tencel & Spandex gives the Groundup Tee not only great next-to-skin comfort but also outstanding performance. Mountain Equipment Groundup Tee specifications: 170g DRI-release; lightweight moisture management with stretch. Semi-fitted active cut for freedom of movement. Tencel cellulose fibres give oustanding odour-free wicking performance. Spandex provides stretch for complete freedom of movement. Crew neck. Tencel: A fabric made from the cellulose found in wood pulp which is processed into a silk-like, delicate fabric. Spandex: Spandex, Lycra or elastane, is a synthetic fibre known for its exceptional elasticity. It is stronger & more durable than rubber.