The Expander sleeping bag liner is made of a super soft and stretchy knitted poly-cotton material. The Rectangular, Traveller and Double models don't have side seams and, combined with the stretch fabric, this offers an unprecedented level of comfort in a budget-priced liner. A built-in antimicrobial treatment keeps odors at bay - and it won't wash out of the liner when it's thrown in the washing machine. This is the perfect travel companion for those looking for a luxuriously comfortable sleep. Features Stretchy, wicking Jersey-knit poly-cotton fabric, knitted without side seams for extra comfort. The antimicrobial finish keeps the liner fresh and odor-free. Easy care – machine wash with no special soap needed. Avoid fabric softeners and dryer sheets. Keeps sleeping bag clean. Packs into its own storage case.