Olli, It is neither, it is an electret type, so it needs bias. The last response curve I saw for that element showed that the response is similar to the HC-5. 73, Don W3FPR Oliver Olli Dröse wrote: > Hi guys, > > can somebody tell me what Heil capsule is in the ProSet K2 that Elecraft sells? > HC-4 or HC-5? > > Thanks & vy 73, Olli - DH8BQA > >