An apparatus for sharpening one or more razor blades secured within a holder is disclosed. The current sensor includes a housing having a Hall effect sensor and circuitry for transmitting a signal indicative of the current flowing through the electrical conductor. The stocking system also includes a conversion controller for switching the inputoutput port between manual and automatic mode. The moving blocks each include contact elements configured to travel on the guide surface while passing across joint clearances each being formed between the track rails arranged in series. The information from the database is compared to information from another source to verify that the proper filter elements are being supplied. The specified period of time is relative to receiving the DLL power-on command.