The three ice-packs are very well made. They have a ring around the rim for a secure fit. There's also a metal piece below the lid that helps. The ice packs do not leak, but they sweat on the bottom from day and night use. My ice packs get to dry out upside down three hours a day because of knee surgery. I keep them by my side on my bed. When I lay them on my comforter melting with ice all night. The comforter is a little wet from sweating on the bottom, but no dripping. It's little water enough where it dries fast. I did screw the top on just alittle crooked once and it did drip. On the few days of just little use which is half the day, I noticed they stay dry on the bottom. They get very cold and feel very good!
UPDATE: I use the day and night and after the ice melts there's a small spot on my bed from the ice pack. I put the strap around my knee and it dripped. That might have been my fault. I don't like how it feels anyway so I do not use the straps. Anyway, one slip after my operation and I'm doomed, lol!