BT-100U cash drawer trigger is designed to provide USB interfacing to the cash drawer. This allows the cash drawer, which is previously connected to POS printer or cash register, to be directly connected to a USB port of the computer. This means through the USB Trigger the cash drawer can be directly connected to the computer when this no printer used in the POS system. The BT-100U USB trigger module uses a virtual serial port driver, making it appear to software like a standard RS232 serial port. This way existing POS software can communicate with the USB cash drawer trigger as though connected to a serial port. A unique serial number is assigned to each USB trigger module and driver software will assign available serial port to each device it recognizes(multiple triggers can be used on one computer). Cash drawer can be directly connected to the computer with BT-100U Powered by USB bus, external power is not required Allows for "Hot Plugging", plug and play connectivity No need to set the COM property Suitable to any cash drawer . Colour:black Material:plastic Package Contents: 4 x BT-100U Cash Drawer Trigger Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.