Class 4 cloaking device
From Memory Alpha, the free Star Trek reference.
Class 4 cloaking devices were a grade of cloaking device utilized by the Klingons during the 24th century, intended for use on small starships.
The Klingons provided the Maquis with thirty class-4 cloaking devices with the Klingon's understanding that they were to be used on Maquis ships against the Cardassians. (DS9: "Blaze of Glory")
