Bar code scanners are designed to read imprinted bar / matrix code symbologies.  Bar code scanners can be slot card scanners, fixed mount scanners, or hand-held scanners.  Slot card bar / matrix code scanners are designed to read imprinted bar or matrix code cards that are passed through the aperture on the reader.  A horizontal scanner is basically a tabletop, where the code is passed over the scanner face.  A vertical scanner sits on top of a counter or stand where the code is passed in front of the scanner face.  A wand scanner is typically made from 1/2" stainless steel tubing or from plastic; the optics are in the front with a cord out the back. The wand scanner must be moved by the user's hand across and in contact with the bar code. While the wand is moving across the bar code, the reflected light is converted to electrical signals through a photocell in the wand.  A hand held or gun type scanner can be non-contact or near-contact scanner, which generally uses a beam of focused light to read the bar code. The most common form of active non-contact scanner uses a laser beam that is automatically scanned back and forth across the symbol at a high rate. Near-contact scanners utilize a CCD device. Active non-contact or near-contact scanners may be stationary as an option.  Gun type readers can also be fitted with optional fixed mounting.