UK mains adapter with LED with Ø5.5 mm (outer) Ø2.1 mm (inner) plug and 1m cable. The plug length is 10mm. Output is 12V DC at 2A (2000mA)

The 12V power supply has ferrite moulded into cable. 

These 12V power supplies are widely used in CCTV cameras, door bells, external hard drives, and many other small AV devices.