Purpose: Keep food fresh and dry. Specification: Material: High-quality ABS material, resistant to high and low temperatures. Non-toxic and durable Size: 9.7 cm * 3 cm Battery: 1.5 V, 2 AA batteries, only alkaline batteries (not included) can be used. User Manual: 1. The machine won't generate heat by itself after being installed with batteries. Press it for 3–5 seconds so that heat will come up gradually. 2. Please use batteries. Don't mix up the polarity of the batteries. Make sure the batteries are properly installed. Otherwise, the machine is not able to generate heat. 3. Long press the machine for 3 to 5 seconds after the batteries are properly installed. Then the machine will start generating heat. 4. For a thick plastic bag, please move it slowly between the machine to let the heat spread evenly for a better sealing performance. 5. No need to remove the batteries. After use, simply move the hook between the machine to block contacts of the two metal parts. Tips: Please don't press the machine too hard. Otherwise, the heating metals may become deformed and broken. The plastic bag for sealing needs to be clean without oil or water.