Home Cinema Packs are surround sound loudspeaker bundles to be paired with home theatre receivers. They’re broken into two camps: standard and Atmos. Standard surround systems are arranged in groupings of 5.1, 7.1, 9.2, etc. The first number corresponds to the number of loudspeakers within the system: bookshelf / floorstand / centre channel. The second number corresponds to the number of subwoofers within the system. Atmos systems are arranged in groupings of 5.1.2, 7.1.4, 9.2.4, etc. The first two numbers are the same as standard systems. And the last number refers to the number of Dolby Atmos or overhead speakers within the system.