All the stores where I live ran out of the usual hand warmers I buy which is "HOT HANDS" so I decided to give these a try I bought them at the "Sport Chalet sporting goods store". What a mistake!  They NEVER warmed up!  I bought 4 packages ( 1 for each hand they are large)..I thought maybe the first 2 where defected so I open up the last 2..and again the NEVER WARMED UP!!!!..even after 2 hrs cold as ever!!!  So I came here on Amazon and found my "HOT HANDS"  I will stick with them..they last up to 10 hours..and they are still hot after 8 hours...FACT!!...http://www.amazon.com/HeatMax-Hot-Hands-Handwarmer-pairs/dp/B0007ZF4OA/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1290902511&sr=1-1