The specifications mentioned could relate to video resolution, frame rate, or equipment used. For instance, "21 mm" might refer to a lens size or a measurement related to the production equipment. "SU Full" could imply a full-screen or high-definition format.
[MEYD-245] Tropical Night – Featuring Meguri (Full Subtitled) tropical night meguri meyd245 21 mm su full
(as indicated in your technical specs) provides an immersive, "up-close" perspective that makes the viewer feel like a participant in the scene. Technical Spec (21mm) Tropical Night Meguri Meyd245 21 Mm Su Full: