Checkweighers make sure the correct weight of a product is maintained for quality control. The product is conveyed over a scale, and if it weighs too much or too little, the checkweigher removes the product from the line. Some checkweighers allow the rejected objects to be sorted into piles. This can be accomplished with a push-off rejector, arms, or a blast of air that redirects messes. Some checkweighers work with various sized load cell conveyors.