A door security system for a door having an electrically actuated lock. The brake has a first position and a second position. Further, there can be provided a resin-coated metal plate excelling in properties, such as corrosion resistance, impact resistance, workability and flavor, and provided, fabricated from the resin-coated metal plate, a metal can and can lid. The system can create and index information on available sales associates, match the customer with at least one sales associate based on the customer, session, and sales profile associate information, and facilitate communication between the sales associate and the customer. The required positional tolerances of the tubes for mating with the remainder of the modular heat exchanger are maintained within the core assembly by minimizing core shrinkage resulting from the brazing operation during which the tubes are brazed to the centers. The transport apparatus continuously transports feedstock of an arbitrarily long length at a desired feed rate, and the grinding apparatus grinds the feedstock transported by the transport apparatus.