Rumpole
Formerly known as "Hercule Poirot"
Did the pictures you noticed have sticker decoration?Right, it could be any type of frame. Based on the measurement of the width in LEs pic the Mat is at least 2". I'm thinking this width would be good for a pic 5x7" or larger.
I did see a couple of Matted and Framed photos on KCs BR wall but they weren't close-up shots so couldn't see any Mat detail.
Have you got a link to them?