This consists of a base containing the lamp, red observation lamp, rheostat and electrical connections. Onto this a holder for 33' of 35 mm diapositive film or an attachment for 2" x 2" slides can be fitted. A separate pressure plate fits the slide attachment to use positive paper. An attachment for the slide copier allowed 3 x 4 cm and 4 x 4 cm negatives to be used with 4 cm wide film. Other fittings allowed for 18 x 24 mm negatives.

Early attachments have a slot for shading parts of the negative, the slide attachment with this example has such a slot. The parts in this example date from different periods. The crackle finish of the slide holder is 1930s. The finish of the diapositive attachment dates to the 1950s, it does not have a shading slot as shown in early illustrations. The shape of the lamp switch varies. Early models of the base housing have the Leitz logo stamped into the metal, later (this example) it is an applied badge. Discontinued in 1957.

The Eldia first appeared in 1927 and remained in production until the 1960s. An accessory mask was used for 24 x 18 mm negatives. The finish of this example dates to the 1950s.