SCBA tank terms are bandied about that can be confusing and rather inaccurate. There is technically no such thing as an 88/97/100 cu ft SCBA tank, though those (marketing/advertising) terms are commonly used (and confusing for people, old pros and newcomers alike). Some also refer to SCBA tanks by their breathing time (which makes zero sense for us, since we aren't firefighters, and time is irrelevant, since it all comes down to one's lung capacity and level of exertion).
Four common sizes of SCBA tanks (yes, there are several more, depending on whom makes the tank) are below. The first two values are actual WATER VOLUME measurements, and are actually the best way to compare sizes, since water isn't compressible, and air is. The other two are kind of thrown about with less precision by various groups:
114 cu in (1.9L) <20 cu ft> <15 minutes?>
285 cu in (4.7L) <45 cu ft> <30 minutes> Actually holds 1,457 L (51 ft^3) of air @310 bar.
410 (6.7L) < 60/73 cu ft> <45 minutes> Actually holds 2,077 L ( of air @ 310 bar; 1,675 L (59 ft^3) of air @250 bar.
550 cu in (9L) <88/95/97 cu ft> <60 minutes> Actually holds 2,790 L (98.6ft^3) of air @310 bar, 2,700 L (95.3 ft^3) of air @300 bar (you get the idea).
The reason for the various cu ft numbers is because air is compressible, so depending on pressure, one can have more or less of an air volume.