Class 4
The term class 4 could refer to:

 Class 4 black hole, a type of black hole
 Class 4 cloaking device, a type of cloaking device
 Class 4 industrial replicator, a type of industrial replicator
 Class 4 microprobe, a type of probe
 Class 4 moon, a type of moon
 Class 4 probe, a type of probe
 Class 4 pulsar, a type of pulsar
 Class 4 stardrive vessel, a starship class designation
 Class 4 tactical vessel, a type of Borg starship

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Class 04