Silicone insulation coverIncreases the effectiveness of the InstantVap vaporizer! Less heat loss. Cleaner device as it captures the oxalic acid that falls off. Remove the dispenser, then press firmly on the vaporizer through the dispenser tube! The silicone must be tightly pressed onto the device, leaving no gap underneath! The silicone cover can be left on the device after use, it does not have to be removed.