To read the bar code the Readers they are necessary; the readers are type different, the employment and the use will determine what kinde.There are readers mono scanning, more scannings and to hight scannings. The quality of the bar code can determine the choice, the position of the code can create some problems, the environment of job has some precise limitations, the resolution of the printers of it can limit the use; everything this involves a prudent choice of the reader to employ.