Description
- Contains super saturated solution of water and sodium acetate
- Chain reaction created by snapping metal disc crystallize solution which gives off heat
- Recharged back to liquid state from crystallized state by boiling in water for 10-15 minutes
- Includes teacherapostrophes guide
- Available in two sizes: 4 x 4 in. and 8 x 8 in.
Технические характеристики
| Includes | Teacher’s guide |
