Pool table manufacturers use slate because it doesn't warp as wood tables used to do.
The slate in pool tables is what makes them heavy. They should also know how many pieces of slate it has and how far the movers will need to take it. Pool table owners should know the make, model, and age of tables. The easiest way to move one is to disassemble and reassemble it at its new location. A pool table is a heavy piece of furniture that needs special care when relocating.
