These are disposable heat packs: the type you stick on your socks and the mini type you stick on your clothes. Duration: 8 hours (for socks) Duration: 10 hours (mini) 5 pairs per bag x 3 bags (for socks) 10 pieces per bag (mini) Expiration Date: 2028.06 (mini) Expiration Date: 2027.06 (for socks) We have checked the expiration dates, but please understand that there may be discrepancies in the listings. * Occasionally, a mix of 2026.06 and 2028.06 may be included. Expired products are not included. Please refrain from bulk purchases. We have lowered the price accordingly. 03