BNC connectors are manufactured in 50 Ohm and 75 Ohm specification versions.

The two types of connectors are physically different from each other. Connection of the two types of connectors is possible but not best practice: Mixing will not give you the best output.
50 Ohm BNC connectors are used with 50 Ohm cables. 75 Ohm connectors are used with 75 Ohm cables.

50-ohm cables/connectors work well with old analogue video formats. If you are looking for a high quality video output, 50 Ohm will not give you a high quality level.

75-ohmcables/connectors are made for high quality digital video and are able to scale their output depending on the input received. They can also be effectively used on the older analogue video formats, which makes them more versatile and flexible - as they can be used in any situation.
BNC cable / Coiled HD-SDI 3G SDI Cable -(Cable length:2ft; 5 ft(1.5 m) when fully stretched) -Straight
SDI Connector :Both BNC male (plug) | Connector: Gold plated | Impedance: 75 Ohm | Cable: 3C-2V Coaxial A/V Cable (About half the thickness of standard coaxial cable with no sacrifice in performance.)
Use PTFE Insulating Material, the coiled sdi cable has characteristics of Good flexibility, High-Temperature Resistance, corrosion resistance. It Copper conductor and silver-plated shielding braid, It has Good shielding, Few Signal Attenuation.
Supports HD-SDI, 3G-SDI, component, composite, MADI, WORD CLOCK, SYNC, etc. bnc coiled cable can transmit up to 1080p resolution for "high quality" HDTV (high definition television). Standard-definition (uncompressed) digital video is also transmitted. Compatible with any device with SDI output, such as SDI HDMI Converter camera or monitor etc.
We are a professional sdi video cable manufacturer, please contact us for customised requirements. If you are unfortunate enough to receive a defective product, please contact us as we offer a one year warranty.