The Montane Mens Dart Long Sleeve T-Shirt is a recycled t-shirt perfect for walking and trekking. Polygiene technology provides permanent odour resistance, helping you stay fresher for longer. Apex thermo eco is an eco-friendly fabric which creates warmth by trapping the heat whilst remaining lightweight creating the close to skin fit which Is usually found in base layers. This product is made from recycled materials helping to reduce waste and safeguard our planet for the future! UPF is the measurement of the level of protection from UVA and UVB rays a fabric provides. This is measured in units, for example UPF 15 allows 1/15th of UV rays to penetrate the fabric. Ranging from UPF 15 to UPF 50, the higher the rating the more protection is provided.