Ssis-137-mr-es.mp4 -

: Usually indicates that the file contains English Subtitles . .mp4 : The digital video file container. What is SSIS-137?

: This is the Label/Producer Code . "SSIS" belongs to the label S1 No. 1 Style , one of the largest and most prominent producers in the Japanese adult industry. 137 : This is the Serial Number for that specific release. SSIS-137-MR-ES.mp4

If you are looking for more details or want to find the official release: : Usually indicates that the file contains English Subtitles