The UP Serac is the perfect top layer for cool mountain evenings, or middle layer for cold flights. Made from a stylish knit fleece, it doesn't just look good - it feels great too. The inside of the cloth has gone through a roughening proces where it is scratched to form a soft and very comfortable surface which feels super soft against the skin, and makes the whole thing more windproof too. The material is 100% polyester, and the Serac comes in sizes M, L and XL.