If you want S-Grade, you are better off getting Tahitian Moon Sand.
so I recommend the T-Grade:
-darker black than eco-complete and sms but still lighter than Tahitian moon sand.
-aesthetically pleasant shape, color and very uniform ~1mm grain size.
-you won't get grains under your finger nails like you do with fine sand.
-heavy enough to hold shallow root plants like HC, and holds a slope very well
-will definitely irritate the nose of small fish who make a living in your substrate, such as loaches, botia, corys, but such substrate surface fish will manage to avoid nosing around your substrate too much and will adapt just fine especially if your tank bottom is heavily planted. if your tank is too bare bottomed and these fish feel threatened by others, then they may try to burrow too often during a panic, and really hurt their snouts.
-However I definitely would NOT use this stuff if you plan on keeping any Eels.
-invertebrates that pick through and around your gravel for food will be fine.
-sucker mouth fish such as Plecos and Ottos will be fine, as will all digging Cichlids.