RealVision 3D Transducer Extension Cable – 3M(10′). RealVision 3D Transducer Extension Cables work with both the transom mounted RV-100, as well as through-hull RV-200 and RV-300 series transducers. Each extension cable features a waterproof, twist-lock connector at the MFD end, and a compatible socket at the transducer end. For best performance, Raymarine recommends using no more than two (2) extension cables in any given cable run..