Holland Electronics GRB-2-B Dual F Connector Coaxial Cable Ground Block
is a zinc anti-corrosive standard Ground block that accomodates Two RG Coaxial Cable Connections and a 12 AWG Ground Wire with ease.

Info. Sheet

This is what you want to use to Ground your Cable TV or HDTV Antenna Coaxial Cable Outside before bringing the Signal Inside. This way, Lightning Strikes and Power Surges have an opportunity to arrest before reaching your TV and Entertainment Electronics. The grounding Block will convey this unwanted Electrical Energy to a Ground Rod via a Copper Ground Wire that you Install (not included). Consult your Local Building Code and NEC for guidance to Properly Grounding your HD TV Antenna, Cable TV, WI-FI, Wireless Internet, Business Band, CB or Amateur Radio Antenna Installation.