What is "octafluorocyclobutane"

Octafluorocyclobutane, or perfluorocyclobutane, CF, is an organofluorine compound which enjoys several niche applications. It is related to cyclobutane by replacement of all C–H bonds with C–F bonds. Octafluorocyclobutane is produced by the dimerization of tetrafluoroethylene and the reductive coupling of 1,2-dichloro-1,1,2,2-tetrafluoroethane.