First find your USB device with lsusb and note the ID. Here, the USB device is the Arduino SA Uno R3 (CDC ACM). The vendor is 2341 and the product is 0041.
root@home:~# lsusb
Bus 003 Device 003: ID 2341:0043 Arduino SA Uno R3 (CDC ACM)
Bus 003 Device 002: ID 0438:7900 Advanced Micro Devices, Inc. Root Hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub