Class 3
The term class 3 could refer to:

 Class 3 containment field
 Class 3 defensive
 Class 3 humanoid
 Class 3 moon, a moon classification
 Class 3 neutronic storm, a type of neutronic storm
 Class 3 nebula, a type of nebula
 Class 3 offense, a violation of Bajoran law
 Class 3 probe, a type of probe
 Class 3 pulse rifle, a type of weapon
 Class 3 surveillance device, a type of surveillance device
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 , another series of classifications

Class 03