Duo Dock

This was the largest and most expensive dock for the PowerBook Duo and the only form-factor offered exclusively by Apple. Unlike the other docks, or "port replicators" that plugged into the back of other laptops, the Duo Dock pulled the laptop inside the dock's metal and plastic case via an internal sliding mechanism (similar to that of a VHS player). The dock turned the PowerBook Duo into a full-size, AC-powered, fully functional desktop computer with all the standard ports.