Get better casting results using solid flasks than with perforated flasks! Tivac Perforated Paper is inserted into a solid flask before investment is poured in. During burnout, the paper disappears, leaving broad channels through which vacuum can be drawn. This method exposes almost twice as much of the investment to vacuum as a perforated flask does. You can use the much less expensive solid flasks, plus you'll be able to fit more flasks in your oven. And Tivac's built-in collar feature eliminates the need for rubber collars, saving you even more time and money. The lock-in feature of the collar ensures that the Tivac Paper stays snug against the flask wall. Available in 2 sizes: 4" or 5" dia. flasks. Each size will fit flasks with heights from 6" to 8". Made in USA.