Having Screw-thread-coupling Contact Patents (Class 439/661)
- Screw-threaded center-contact type (Class 439/663)
- Plug having screw-thread-coupling contact and also having resilient or spring-biased center contact (Class 439/664)
- Having mutilated, irregular, interrupted, or discontinuous contact thread (Class 439/665)
- Receptacle having internal screw-thread-coupling contact (Class 439/666)