Smokin' Tubes...the end opposite of the open end is capped, fill the tube with smoking pellets then hit it with a small torch to get 'em going, once the fire is out and it's smoking, lay it in the bottom of the grill on the charcoal rack or even on the food rack, or can be used to supplement and add more smoke to an existing smoker with chip or chunk trays/holders. They come in square, round, or octagonal fashion...I prefer the square so it doesn't start rolling around on the grate when you're in and out of the grill/smoker. These things basically turn any grill whether gas or charcoal, into a smoker. With the 12" smokin' tube pictured above I posted, loaded can get about 3-5 hrs of smoke time out of it, then reload with pellets if necessary. Could probably use smoking chips packed pretty tight so they touch each other and still catch and smoke as well, just haven't tried any chips yet.