Clear-Com main stations and power supply units are all equiped with 3-pin XLRs on the rear panel to support a single channel of intercom, this makes them directly compatible with single channel beltpacks like the RS-601 or RS-501 series packs, these are equipped with 3-pin loop-thru XLRs that allow the use of standard 3-pin XLR microphone cable. 
RS-502 / RS-602 beltpacks use a 6-pin XLR cable to support the use of two channels on one beltpack, but that also means these series of beltpacks cannot connect directly back to a main station or power supply without the use of an adapter cable that can take two seperate 3-pin XLRs on different channels at the mains station or PSU and combine them on a single 6-pin XLR cable. 
Clear-Com makes an adapter cable, called the YC-36 (shown below) which takes two 3-pin XLR female connectors and wires them into a single 6-pin XLR male connector.  This allows the use of 6-pin XLR cable to connect RS-602 beltpacks together in series which properly supports two seperate intercom channels on one cable.