Suitable for the following models:
ThinkPad L412
ThinkPad L420
ThinkPad L421
ThinkPad L512
ThinkPad L520  
ThinkPad T400s
ThinkPad T410
ThinkPad T410s
ThinkPad T420
ThinkPad T420s
ThinkPad T510
ThinkPad T520 Dual Core models only 
ThinkPad X220     

The ThinkPad Port Replicator Series 3 (433610W) offers convenient, one-step connection to the devices you use every day. You can access your LAN or Internet connection, VGA analog monitor, and USB attach peripherals with one simple click.

Features and benefits:

Left corner alignment for easy system attachment
Convenient eject button for one-step system removal
4 USB 2.0 ports
VGA analog monitor port
RJ-45 Ethernet port
Cable lock slot physically secures the ThinkPad notebook and ThinkPad Port Replicator Series 3.
When a cable lock is inserted into the lock slot on the back of the ThinkPad Port Replicator Series 3, the cable lock secures both:
ThinkPad Port Replicator Series 3 to the workspace (desk, wall, pole)
ThinkPad to the ThinkPad Port Replicator Series 3, via an internal locking mechanism.