Box with Lid for 4.25" x 2.50" Glassine Envelope Organization.
The box/lid have a 4mm offsetting surface to lock them together. 0.4mm face offset for tolerance.
There are also spacers included. 2mm and 4mm.
The inside dimensions are LxWxH - 109x80x65mm
These types of envelopes are used in hobbies/collecting (Stamps / Philately for example)
An example of the envelopes that work with this box : https://www.amazon.com/dp/B00N16H4HC