Will this work?

The fire grates on my Silver Smoker keep getting trashed by the heat of the charcoal/wood fires I use to smoke butts and briskets. I was in my local Lowes yesterday and they are clearing out all their BBQ accessories now that summer's over. I found a couple of Char-Broil adjustable lava rock grates normally $29.99 on sale for $7.65 each. These are very heavy duty metal with 3 different legth sets of legs for varying heights. I checked the measurements and they will fit in my firebox perfectly. Question is, since they are intended for ceramic/lava briquettes that probably don't get as hot as direct contact with RO lump and mesquite coals, are they going to hold up? As a bonus, if I use the longest set of legs, I will get an additional couple of inches clearance under the coals so I won't have to clean out ashes so often over a 12-16 hour cook. Any opinions?

They're not cast iron, just some thick rod stock. Not chromed or porcelain coated, either. I'm gonna leave one shrink-wrapped for the future and do some sort of seasoning on the other before I actually cook with it. I guess at seven bucks, if I get one season out of it, I've done okay. The things must weigh about 10 pounds apiece, so whatever it's made of it might last awhile.

I'm not going to put meat on them, they are going to be used as fire grates in the firebox of my offset smoker. I have cast iron cooking grates in the smoke chamber. The thin chrome grates that come with the cheap offsets like mine don't last long when they have a pile of burning RO lump and a couple of mesquite chunks sitting on them for 10 - 12 hours while you're trying to get the brisket done. I am hoping these things will last a couple of years so I don't have to keep calling Brinkman to send me new fire grates.