They are all plastic with little textured rubberized mini-mats on the areas that touch the DX. Also bottom is totally covered with the rubberized mat so it is non-skid. They are about half the height of the DX, when it is upright with a broad base that will not tip over easily.
Overall feel is sturdy, not cheap, although they don't weight a whole lot, being black plastic. But nothing flimsy about them. I bought the two-pack (with 2 cables) and have on my desk and the other sort of at-large around the house or office where I will be working.
Only drawback is the size that doesn't accommodate the portrait DX, just the landscape position. Apparently, a redesign will accommodate the portrait. Not sure when that will be available, if not already.