The SUM-PSPP cable is a 1/4" Male TRS to 1/4" Male TS Stereo to Mono Summing Cable.
The EWI SUMMING Cables are purpose built to combine stereo left and right outputs into a single mono output. These cables combine the signals utilizing a resistive network which avoids the problems associated with simple hardwired combiners (phasing issues, loss of low end and general poor sound quality).
These cables are constructed with EWI model MSM-2650 cable, which is a 26ga. twisted pair spiral shield cable and assembled with EWI cord ends in four different combinations. The 3.5mm (1/8") TRS end has been designed to fit into most device output jacks even if a protective case is installed.