The Optoma Mini USB 4P to USB A 1 Meter Cable for the PK201 And PK301 Projectors allows you to connect these Pico Pocket Projectors to other devices like laptop and desktop computers.
The one meter (3.3 foot) cord has USB A connector on one end. This is what you might call the "regular" kind of USB terminal because it's the kind most laptops and desktops have. If an advertisement or article doesn't mention the type of USB port a machine has, you can be pretty sure it's Type A.
On the other end of the cable is a small mini USB 4P terminal. That's the kind built into the PK201 and PK301 Pico Pocket Projectors. So with this cable you can connect your Pico to other common devices like your laptop computer.