From Truetone:

The 1 SPOT is the original 9V pedalboard power supply that only takes up one spot on an outlet strip or wall outlet. It solves an annoying problem that people have complained about for years, and does so with quiet, reliable performance!

• Handles from one to well over twenty guitar pedals (1700mA max!)
• Triple filtered output for clean, quiet power
• Heavy-duty output cable.
• Use with optional multi-plug cable(s) for powering more than one pedal.
• Guaranteed to work with over 90% of the effects pedals on the market!
• With optional converter plugs, the 1 SPOT will work with virtually ANY 9V pedal! …even Line 6 modeling pedals! **
• Will even convert international voltage (100V-240V) automatically; no transformer needed!
• 3 meter (10′) cable is almost twice as long as other adapter cables.
• Only takes up ONE position on your outlet strip or wall outlet!!