The EM Custom Loopbox4 is a compact, four-loop slave MIDI looper designed to expand the routing capabilities of MIDI-controlled pedalboard setups. It utilizes high-quality relays and a true bypass circuit to ensure that non-MIDI effects pedals can be switched in and out of the signal chain without tonal degradation. The unit is designed for ease of integration, featuring a learning mode for incoming MIDI messages to quickly assign switching commands. Built into a durable steel case, it operates as a space-saving solution for managing multiple effect loops via an external MIDI controller. This device is particularly effective for offloading switching duties to a remote or master controller while keeping pedals accessible in discrete loops.