If you want to sit 8 inches of the ground
These are not for a dining room table
Depends on how much weight you're planning on holding up I'm using 1 inch screws to hold up 25 to 35 pounds
I got a small cabinet holding up by these legs that's about 50 pounds or a little better
The height is 8 inches.
Their held in with four screws so it depends on the size screws you use I'm using mine to hold up a hutch that four feet wide by twelve inches deep and thirteen inches high which weighs about twenty five to thirty pounds and each leg has four one inch screws
Two and a quarter inches