⌘ K

Help...what piece is this?

Thrillho · 2015-05-04T01:17:10.000Z

See photo. I found this base plate, but I'm not sure where it's from or even what brand it is. The only writing I can find on it is "J & B Taiwan". It measures approximately 24" x 15". The blue sides are shaped like I-beams, so maybe it's part of a bigger table or something? The "dots" don't have a lego logo on each one, but instead just a small circle.