I followed the instructions at http://who-t.blogspot.de/2014/12/building-a-dpi-database-for-mice.html to measure the DPI of another USB mouse. The result is to be found below:

# Logitech USB Laser Mouse M-UAS144 [LS1 Laser Mouse]
mouse:usb:v046dpc062:name:Logitech USB Laser Mouse:
 MOUSE_DPI=1200@125

$ udevadm info /dev/input/event18
P: /devices/pci0000:00/0000:00:13.0/usb7/7-3/7-3:1.0/0003:046D:C062.0006/input/input20/event18
N: input/event18
S: input/by-id/usb-Logitech_USB_Laser_Mouse-event-mouse
S: input/by-path/pci-0000:00:13.0-usb-0:3:1.0-event-mouse
E: DEVLINKS=/dev/input/by-id/usb-Logitech_USB_Laser_Mouse-event-mouse /dev/input/by-path/pci-0000:00:13.0-usb-0:3:1.0-event-mouse
E: DEVNAME=/dev/input/event18
E: DEVPATH=/devices/pci0000:00/0000:00:13.0/usb7/7-3/7-3:1.0/0003:046D:C062.0006/input/input20/event18
E: ID_BUS=usb
E: ID_INPUT=1
E: ID_INPUT_MOUSE=1
E: ID_MODEL=USB_Laser_Mouse
E: ID_MODEL_ENC=USB\x20Laser\x20Mouse
E: ID_MODEL_ID=c062
E: ID_PATH=pci-0000:00:13.0-usb-0:3:1.0
E: ID_PATH_TAG=pci-0000_00_13_0-usb-0_3_1_0
E: ID_REVISION=3100
E: ID_SERIAL=Logitech_USB_Laser_Mouse
E: ID_TYPE=hid
E: ID_USB_DRIVER=usbhid
E: ID_USB_INTERFACES=:030102:
E: ID_USB_INTERFACE_NUM=00
E: ID_VENDOR=Logitech
E: ID_VENDOR_ENC=Logitech
E: ID_VENDOR_ID=046d
E: MAJOR=13
E: MINOR=82
E: MOUSE_DPI=1200@125
E: SUBSYSTEM=input
E: USEC_INITIALIZED=339348432