Our Cub came with a PS Engineering Aerocom III. The cords were fraying and finally it was no longer usable. We saved money by replacing it with a Pilot USA portable intercom, the model with a built-in connector for our ICOM A-6 radio. The PS Engineering unit had much, much better sound quality and the auto squelch really worked great in the Cub. I never tried it with the door open but have heard it handles that situation well. The Pilot USA unit has worse sound quality and you have to adjust the squelch, but the connection to the A-6 is a little bit more convenient than the adapter required with the PS Engineering unit. I would choose PS Engineering if I had to choose again.