Be-type binary components showing long non-orbital photometric periods I summary the case of Double Periodic Variables (DPVs), interacting binaries with a (usually) Be-type primary component showing a long photometric cycle about 33 times longer than the orbital period. Photometric and spectroscopic characteristics of DPVs are given and the case of the prototype V393 Scorpii is presented and compared with the relatively well know object beta lyrae. We present a method for disentangling spectral components and another one for studying the evolutionary stage of DPVs. We show evidence for a massive circumprimary disc around a Be-type critically rotating primary in V 393 Scorpii and argue that the long cycle is produced by a kind of modulated high latitude wind.