The nRF24L01 is a single chip 2.4GHz transceiver with an embedded baseband protocol engine
(Enhanced ShockBurst™), designed for ultra low power wireless applications.
The nRF24L01 is designed for operation in the world wide ISM frequency band at 2.400 - 2.4835GHz.
An MCU (microcontroller) and very few external passive components are needed to design a radio system with the nRF24L01.