A containment apparatus for a multi-pass oven consisting of guide rails and tapered guide chutes having side rails. A tapered guide chute directs product pieces from one conveyor to the center of a receiving region of an underlying conveyor. Guide rails are placed along the sides of the receiving region of an underlying conveyor and maintain baking product pieces on the conveyor. Diverters on the distal end of each guide rail further move product pieces toward the center of the conveyor. Such diverters help ensure that pieces reach a subsequent guide chute or subsequent conveyor without falling off of the conveyor. Such guide rails, diverters, and guide chutes help prevent damage to, and loss of, product pieces while pieces pass through the oven. Guide rails, diverters, and guide chutes are particularly effective at maintaining round or cylindrical pieces within a multi-pass oven.