These are great. To COMPLETELY recharge, you must nuke them several times for about 30-40 seconds, letting them cool for a while between nukes. What I do personally is squeeze the bottom half of plastic and seperate, then pour beads onto paper towel and nuke 4 or 5 times for 40 secs, cooling completely in between nukes. Then carefully pour back in (after beads are cool) to bottom half, making "mound" of beads at top, then put lid on. Must be cool or there will be condensation.
Have to say not bad stuff. Although it does not completly change back to blue when you dry it out in the microwave. I have 4 of them in my 1/2 ton liberty safe - 5ft High x 3ft Wide x 3ft Deep