HT12D and HT12E are encoder and decoder IC for RF transmitter and receiver. Any project with an RF module requires these ICs.
The pack has HT12E (Encoder), HT12D(Decoder) and 2 pcs 18 pin IC base. IC base is for the safety of Ic while soldering on PCB. IC base Prevents it from getting damaged due to excess heat during soldering also it makes easy to replace