Porcelain E27 Lamp holder with cable clamp.
Height: 6 cm.
Diameter: 4,5 cm.
Plastic cable clamp.
This lamp holder has a security system that, in order to protect you from electrical shocks while you are changing the light bulbs, does not allow it to unscrew.
If the necessity to unscrew it should present, it is possible to unblock it by pointing at the security flap you will find at the base of the lamp holder with a screwdriver, while you are turnig the lamp holder.