These are constructed at the most advanced level of “ultra low power” communication protocols: they use broad band (2.4 GHz) communication, but with systems of access to the channel that prevent collisions and errors.

They contain control software that allows them to independently select the HUB to connect to so as to minimize energy consumption, but above all to communicate in atwo-way direction with the network to receive price changes and communicate their battery level, signal level and any changes in position (for example, due to accidental falls or theft).

• LCD or electronic ink display (the future or low power displays, able to display graphics), designed for maximum price readability (almost 2 cm high).

• Average life: up to 7 years

• Total surface area from 1000 to 6000 mm2