They are 30 x 30 cm. squared floor tiles, so four of them make a perfect 60 x 60 cm. DBA board easy to transport and to store. I bought four of them for 9 euros; it could be a little expensive but it isn't when compared to other DBA mats in the market. I bought them all in green so I didn't have to paint or flock them.
I'm quite happy with the result. What do you think about it?