Jewelry Smelting Gold Silver Set Kit Ceramic Foundry Crucible Tongs Flux 17A Works with gold, brass, silver, copper, aluminum, and more The ceramic crucibles can withstand temperatures up to 2500F (1371C) Includes a pair of small whip tongs, plus a larger size that will securely hold the ceramic crucibles (this kit comes with the following sizes: 100 gram, 250 gram, 500 gram, and 750 grams) *Use smaller tongs for the smaller crucibles, and the larger accommodates the 500 and 750 gram crucibles Also features a 1 Kg graphite-clay foundry crucible, flask tongs, two 5/16" in diameter x 12" long graphite stir rods, and a 6 ounce package of anhydrous borax casting flux