Whats inside the bead at the end of the laptop charger?

The Bead at the end of the charger or any other devices like the mouse

You guys might have observed the bead at the end of the laptop charger.But have you wondered whats inside it?So here it is.
It is actually a choke(to talk in general) or the ferrite bead.These chokes(ferrite chokes) will ensure that signals are sent only in the intended directions and no EMI is transmitted between the peripherals. The choke dampens these EMI waves by acting as an EMI blocker. The blocking is most effective when it is near the source of the EMI, thats why you will only find these ferrite beads near the end of the cables.These tiny cyst-like beads make sure that our computer peripherals work properly and don’t cause any issues for the computer itself. 
Source:http://goo.gl/cFZhk7