More interestingly, the devices share both power and data through pin connectors on the top and bottom of each device. This lets the abilities of one to work with the other: Snap the Bluetooth speaker to the 10,000mAh battery, and get nearly a full day’s worth of music (or a lethally lengthy conference call). Snap the router to the hard drive, and your files can be accessed from your own personal cloud. A maximum of five devices can be stacked together, but the current kit contains only four. Lenovo says they’re considering adding additional devices to the Stacks lineup. A compact projector would be a nice addition, as would an AC adapter for ThinkPad laptops.