Shoddy craftsmanship. You're better off to go to a brick-and-mortar store to see and feel what you're buying. Got stuck with one of these after paying a grand online. The mat was glued on crooked, and the board is imbalanced. I might as well have thrown the money out the window, because I ended up buying a new board after a couple of uses. Live and learn. Buying online nowadays isn't worth the gamble because there are too many unscrupulous sellers.