Thinkpad Port Replicator II 74P6733 Docking Station - X31,etc

Compatible with X20/21/22/23/24/30/31, T20/21/22/23/30/40/41/42/43, R30/31/32/40/50/50p/51/52, and A20/21/21e/22/22e/30/31 (Does not support X40/41, R40e/50e, or G40)

Pass-through (replication) of ThinkPad notebook ports including Gigabit ethernet (RJ-45), including modem (RJ-11), USB 2.0, DVI, VGA, serial, parallel, PS2-keyboard, PS2-mouse, diskette drive, audio line-in and line-out.
On/Off switch
Includes a slot for an optional cable lock

An integrated system tray provides a stable fit and comfortable typing angle
One easy step eliminates the hassle of connecting multiple devices one-by-one to the ports on the ThinkPad system
Gigabit Ethernet pass-through port (will function as 10/100 ethernet port for system without gigabit ethernet).
USB 2.0 pass-through port (will function as USB 1.1 port for system with USB 1.1).
Power pass-through -- use the AC power adapter that ships with your ThinkPad or with an optional power adapter.