Product Number: SB47058
In Stock (Ships within 1-2 business days)
Contains a super saturated solution of water and sodium acetate. Snapping the metal disc creates a chain reaction, causing the solution to crystallize. The crystallization process gives off heat. Packs can be recharged back to the liquid state by immersing in boiling water for 10-15 minutes and allow it to slowly cool. Includes teacher’s guide. 4 in. x 4 in. Grades K-12.