The Sum+Inv from After Later Audio is a compact unity-gain mixer with inverters. The module is only 2HP wide and combines two similar mixer units, each combining and outputting two audio or CV signals. At the INVert output the 180° rotated signal is available. With audio this is practical to avoid phase cancellations with stereo patches, with control voltages you get opposite modulations. The lower mixer has the special feature that the output signal of Out1+2 is normalized to input A, therefore the module can mix up to three signals on Out/Inv A+B and also invert them.