Seal your perforated flasks for investing with this easy-to-use disposable Shrink Band. Slip band over the flask, then simply apply heat to shrink it tight, sealing your perforated flask. You can use a steam dewaxer, hot water or a heat gun to shrink the band. Bands are easy to remove, too; simply peel them off the flask after investing. They leave no residue, so no extra clean-up is needed.