Long-lasting kairo pocket warmers

Magma non-adhesive warmer

Brand: Kirigai

Price: 280 yen

Place of purchase: Sugi Drugstore

Rating:

The big, bold characters マグマ caught my eye and I decided to pick up a packet of five for less than 500 yen to give to friends. Magma lives up to its product name. It's made from paulownia ash, iron powder, and salt, likely stretched with vermiculite. The chemical reaction which starts as soon as you take the plastic wrapper off takes less than a minute. I popped one in my pocket and found it pleasantly warm. They're great tucked into the small of your back. Like it says on the package, Magma is hot for 12 hours.

This version does not have an adhesive backing, but I didn't miss it. The packets fit well in pockets, and I simply tucked one into the waistband of my trousers and it stayed put. But you have to be careful with these things - don't use them directly against your skin, or sleep with one, or use them while you're ensconced in the kotatsu. The maximum temperature ran soar to 73 degrees (the average temperature reaches 61) and could burn you. And the product does what it says - it really lasts 12 hours. I got a whole day of heat out of one.