※The main unit is for display purposes only; the product is the case itself. We've created a case with the perfect size and inner diameter for both the receiver and transmitter, allowing them to be stored in the smallest possible size without shaking. External dimensions are width 54 x depth 45 x height 93mm. While we're not sure if it was a perfect fit, we've received feedback that it could also be used for 20L. The lid snaps shut securely and is difficult to open unintentionally, but it opens with a click when pressed from the side. There's no chance of it falling open when turned upside down. Therefore, you could attach double-sided tape to the back of the lid and stick it directly to an effects case (^^). There's no corner interference during opening and closing, which is common with this type of product, and operation is very smooth. We had some concerns about leaving it directly on a surface during charging, so we've designed it so that you can plug in the charging cable while it's still stored in the case.