This is a Moog Subsequent 25. It's been tested thoroughly and all functions behave as expected. A great way to achieve that legendary Moog bass tone while preserving access to modern niceties such as presets and keyboard transposition. Best of all, unlike most Moog ladder filter synthesizers, this does not attenuate the low-end when filter resonance is employed. No need to choose between melting subwoofers or melting faces - you can now melt both!