A speaker or subwoofer cabinet that has no port. In general, a sealed-cabinet speaker or subwoofer has less low-frequency output but better transient response than a ported cabinet.
A sealed subwoofer can also take better advantage of available room gain, thereby exhibiting very deep in-room extension.
Generally speaking, sealed-cabinet subwoofers are also smaller than their ported counterparts.
SVS offers both ported and sealed subwoofers.