This is Stereo to Mono Converter is a L/R audio signal and provides two identical mono outputs.
Easy to connect between stereo source outputs and right/left inputs of a power amplifier with no power required.
The input and output connections are both RCA connectors.
It is a perfect solution for summing 2-channel/stereo line level outputs to a single channel/mono signal.
It is superior and more electrically correct than using a Y cable which may cause damage to outputs.