Basically a Sa spiral arms are more tightly bound than a Sb. A Sc has very loose spiral arms.
See related link for a pictorial
Stereo System =SC-AK770 Main unit = SA-AK770 Front speakers = SB-AK770 Subwoofer = SB-WAK770 In short, the SA-AK770 would be a stereo with no speakers or subwoofer.
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NGC 3486 is a type Sb spiral galaxy.
SB are for Skateboarding and regular blazers are just meant for eaither basketball or casual.
uzuki engine versus Briggs and Stratton