It's an acrylic. I was sent some samples a while back an do not find it suitable for knife handles at all. It's very "chippy" when working, and in anything less than 3/8" thickness, is very fragile. Cold is the worst....when it gets below freezing temp, its about as fragile as a piece of ice. As a test, I ground a 4" X 1" piece to just under 1/4" thick, and dropped it on the shop floor.....it broke into three pieces.
Depending on the "filler" used, drilling holes in it is worse than pearl.....badly chips on the exit side no matter how light you are on the drill bit......backing or taping over the exit side doesn't seem to help.
I think it's pretty "cheesy" stuff, and would not consider using it on any knife I produced.