Laptop docking station external interfaces lan rj45 usb 20 ps2 x2 audio out serial port parallel audio in esata video outputs dvi 2x vga displayport 2x usb 20 ports 6 compatible with hp elitebook 8440p hp elitebook 8540p hp elitebook 8540w hp probook 6440b hp probook 6540b hp probook 6545b