The Weber Smokey Joe charcoal is a replacement part for the grate which the charcoals sit on at the bottom of the barbecue kettle not the grate on which the food on sits at the top of the kettle.
With the hot coals sitting directly on top of the charcoal grate and cooking juices falling onto the coals the grate can become pitted and tarnished or burnt on food residues can detract from the taste of cooked food.
The Weber Smokey Joe Charcoal Grate means that a Smokey Joe's charcoal grate can be returned to it's original state when it was new.