The C2 HM series receiver is the biggest size unit. After that it has been designed to minimize the aesthetic impact on the on-board system.
The receiving antenna can be easily screwed onto the SMA type connector. This particular makes it easier to move it to a different location. OPTIONAL It's possible to mount an external antenna with 2 or 5 meters cable, in this way you can install the antenna in a better reception place allowing the receiver positioning even inside an electrical panels or metal structures.