1 .long time warm 2. just need 8-12 minutes to heat it 3. explosion-proof technolgoy 4. Safe and reliable 1.diameter--21.5CM2.you can use it to warm hands,feet,kness,stomach,back and any body place you want.3.it can promot the blood circulation,good to health4.many shapes you can choose from,we have many images and type for choose5.it is very safe to use,pls be rest assure of that,and it is ...