This is the Behringer 2500 series OSCILLATOR MODULE 1004. An authentic reproduction of the original ÒSystem 2500Ó circuitry from the 70Õs that can fit in a standard Eurorack case. The best part? ItÕs at a very affordable price. Mix the OSCILLATOR MODULE 1004 in with your existing rig or start your modular synth journey from here. Either way youÕre sure to have a lot of fun.