long story short, my grandpa received a gas grill that "didn't work" to scrap out. I asked my grandpa if I could look at it to see it was salvageable and he said yeah. After ALOT of cleaning I hooked up a propane tank a fired it up

this is the best looking/working grill ive owned. The only problem was the igniter broke. I just finished some ribs up a little bit ago and they were my best to date, ive never cooked them so slow in my life. 275* for almost 4 hours
It has the IR burners, what are they best used for?