George's estimate of the weight is pretty close. The upright marble or granite headstone weighs approximately 230 pounds, and measures 42" x 13" by 4".

There are other, lighter types of markers available from the VA --

Flat marble or granite -- 130 pounds, measuring 24" x 12" x 4"
Flat bronze -- 18 pounds, measuring 24" x 12" x 3/4"
Bronze niche -- 3 pounds, measuring 8.5" x 5.5" x 7/16"

Manhandling (or womanhandling) a 230 pound marker will be a chore, but I did it a few times before my back went bad (wonder if there's any connection), and I considered it a small sacrifice to make to honor an old soldier. The lighter bronze marker is very nice, too, and I've planted a few of them in the past. You'll need to pour a cement base with slightly larger dimensions than the marker. I allowed for an extra half-inch on each side, but I've seen them larger. It's a matter of personal taste, I guess.