An adapter (or adaptor) is a device used to match the physical or electrical characteristics of two different Connectors so that a connection may be made between them and the Equipment You desire to Cross-Connect. Most Connections for Video and RF (Radio Frequency) Equipment is 75 Ohm in Characteristic Impedance. Radio and Microwave Frequency Connections Passing High Power Require 50 Ohms. A Majority of the Adapters offered Here are 75 Ohm. However, with the High Quality Dialectric Found Surrounding the Interior of the Mating Connection, Low Power Usage, and Transition Impedance Matching of Like Characteristic Impedances, Resulting Mis-match of 50 Ohm use woiuld be so Low as to be Considered Negligible.