The RockBoard MOD 4 - All-in-One Wireless System Receiver + Patchbay for Pedalboards offers an easy-to-use wireless connection between your instrument and your pedalboard, featuring digital wireless technology that delivers incredible audio quality, a simple setup procedure, and reliable use for any gigging musician. The wireless system works in the 2.4 GHz ISM band for unlimited worldwide use and offers a full 20 Hz - 20 kHz frequency range with only 5 ms of latency. The patchbay module is designed to route connections from underneath your pedalboard to its front, giving you a central access point and tidying up your connections. The A, B, C, and D TRS sockets are wiring thru-connections from the front of MOD 4 to the corresponding sockets on the back. This allows you to connect your pedals permanently underneath the board, so you only have to connect cables to and from the front of the board, instead of having to route underneath it when setting it up for a gig.