The ultra-thin ThinAir Performance Socks offer comfort, support and air-flow technology. The signature OS1st Compression Zone Technology is put to use with SkinThin material on the top of the foot for heat expulsion and two softly knitted "lift bars" to push cool air back into the sock. The socks also feature antimicrobial silver-ion treatment, moderate compression at the arch for comfort, and ultra-soft but durable microfiber.