Frap Tools 321 is a logic module for modular synthesizers in Eurorack format. With the module, audio signals or control voltages can be increased in level by up to +6 dB, phase-inverted and shifted via the DC offset function. Frap Tools 321 provides three channels for this purpose. In addition, the 321 can generate CV signals itself, allowing it to be used as a (macro) controller. In addition to individual outputs, there are two summation outputs with damping switches. The right one of the sockets outputs a mix of all processed signals and the left socket outputs voltages generated by the module itself.