The A-142-4 has jumpers at the back and you can freely select which of the four envelopes you want to loop. This way you can create some interesting rhythms or even use it as a clock to drive your sequencers and clock dividers! Of course, it works best for pinging filters and low pass gates. At its shortest decay setting the envelope is just perfect for A-101-2, Borg, Pittsburgh LPG or just about everything else! 4 envelopes in just 8HP... A must, especially in smaller systems.