Stop sweat from running in your eyes with a high tech wicking material that pulls sweat to its top layer and evaporates it continuously, leaving your head cooler in the summer and warmer in the winter. The back SMS layer also traps oil, salt and odors increasing the hygiene and comfort for the wearer (and those around you!). One size fits all. For optimal performance with everyday wear, use one to two liners per hard hat, baseball cap, or other head gear per week then throw them away! This award winning product was used by 2008 Olympians to keep them cooler under pressure. 10 liners per box. Made in China.