Having a few USB 3.0 external hard drives, I was wondering how to safely stack them to economize space while still allowing good airflow or ventilation between them. Then I came up with the idea to purchase and use this product. I bought two sets of these (three trays each) and they worked fabulously to solve my dilemma. The great thing about these for the purpose I am using them is the metal screening that contributes to the airflow and venting process of the external drives I have sitting in them. These quality metal mesh trays solved my problem and I can now stack my drives safely without impeding airflow between them! The solution also came at a nice, affordable price!The company that sells these is also great to work with as I needed some extra pins (used to hold these in place when stacking them). I called their support and they sent me a whole bunch of extra pins, more than enough to cover my needs. They're considerate, easy to work with and they stand behind their product.Although I found that there's more than one use for these things, you can rest assured that they are a quality product also for the intent for which they were designed (desk organizer). This is a great product and company!