This unit appears to be modified compared to the original D2(see last 7 pictures for example). tested in good working order. the lamp is ariso w45 but looks the color temperature is different the my another D2 lamp. the unit does not have defuse disc comes with it, sold as is.

Aristo model D2 cold light head for installation on Omega D-2, D-3, D-5, D-6, D5500 4x5 condenser enlargers, and Beseler 4x5 enlargers. On Omega condenser enlargers, the self-contained lamp head is inserted in the condenser spinning in place of the main condenser lenses. To accommodate the power cords, a notch can be cut in the spinning, or the original incandescent lamp cap can be removed and the cords routed up and out the top of the lamphouse.

On Beseler 4x5 condenser enlargers, the lamp head is similarly installed in the condenser lens housing. On Beseler enlargers equipped with a 4x5 dichroic colorhead, the mixing chamber can be removed, and the Aristo head inserted in the mounting collar, with the power cords routed out the top of the lamphouse.

This unit is supplied with W45 type lamp, recommended for printing on graded B&W papers.