This is just what you need to store your pH meters. I have found that while this works very well some meters are already not waterproof and therefore will not hold any solution. In this case you have a small sponge in the lid to retain moisture. I recommend carrying this product with you before using your PH meter There is a certain PH value associated with cleaning with distilled water as a solution.Please never use distilled water as a storage solution as this will destroy your device.