a laser scanner capable of reading bar codes (see UPC, EAN, etc.) There are a wide variety of these , some of which do their own decoding, and some that rely upon software or other devices to do their decoding. BCR are usually attached to a POS system either through a keyboard wedge or a serial connection. Not every BCR reads every bar code symbology. Some read only UPC, other only Code 3 of 9, etc. Also, some BCR are more sensitive to density, size, angle, etc. than others.