We use wood base, it won't be deformed under long time use, it is more stable to put on the sofa, table or the back seat of the car, etc.
The surface is a soft silicone material, which allows drinks and other stains to be cleaned with just a quick wipe.
We use food-grade silicone, BPA-free, odorless and non-toxic, which is more secure to use.
We put non-slip pads on the bottom corners to make it less likely to slip off the couch.