Holds 12 large trays! Each hole is approximately 13.6mm high, 142.2mm deep and 96.5mm wide. It’s designed to take our trays that are 93.9mm wide, 160mm deep and 11.3mm tall with a bit sticking out to grab.
There are ridges to locate the holders on top of other holders of the same size – I recommend gluing them if you’re going to be stacking them but if you’re careful that may not be necessary.
Trays are an optional extra – and they come with plugs that have little handles on them to make getting them in and out easier.