That's all I use. Here's a safe and easy way to get them. I took 6
regular concrete blocks piled 2 high in a U-shape. There's about 14"
between the side blocks. On top of that I have an old refridge metal
rack. Some of the rods cut out so there's a good 1"-2" between them.
On top of that I have 2 sections of square ceramic chimney flue, 1 on
top of the other. I build my fire on top of the grate. Every so often
I bang the bottom of the metal rack with a long handled shovel, and the
embers (coals) fall down. With the shovel, I put them in the small part
of my offset grill. Just put more pieces of wood down the "chimney" as
needed. Works great.