GM812-S lens reading distance is 5-30cm.(The actual data depends on the size and content of the code)GM812 series bar code reader module is a high performance scanner, can read 1D bar code and read 2D bar code with high speed. It also high speed for linear code, even for bar code on paper or screen.GM812 series bar code reader module is an advanced bar code decoding algorithm which developed on recognition algorithm, can and accurately read bar code, secondary development.material: metalColor as shownPackage Contents:1 pcs Barcode Scanner ReaderOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.