If you have a Weber kettle grill and want to use it for low and slow barbecue cooking, the Smokenator makes it easier. The Smokenator is an insert tool for the 22" Weber kettle grill.
You can see it's a sheet metal partition, enclosing charcoal briquettes and shielding the food from direct heat. The other innovation is the proximity of water to the coals. The cooking environment is controllable from 100 percent humidity to completely dry. The unit will hold fuel for 6 hours and will hold 230-240 deg f dome temperature in a steady state condition for hours (210 deg f at the food support grill.) The directions are superb and a complete novice can low and slow cook without much effort saving following the instructions.
The inventor of the Smokenator also provides a 17.75" diameter collapsible grill that effectively raises the total cooking surface to about 550 square inches.