A great feature packed 5 stage envelope generator with expander and two looping modes (one of which I think is unique). Check out the other Erica Synths Black Series videos here –

Black Varishape VCO –
https://www.youtube.com/watch?v=TabnHI7NQ9M

Black LFO –
https://www.youtube.com/watch?v=L8Nn8aqSMSE

Black Digital Noise –
https://www.youtube.com/watch?v=Wflf0TK9YAY