Vivitar and other trays use plastic clips. Some customers over the years have identified easier slide changing with brass clips. For slide projectors by Honeywell Trays made by the Airequipt factory. These trays work upright like a ferris wheel. These trays fit only a limited number of Argus models.
Tray lays flat on the surface of the projector.
Long out of production these are available only as USED products. For efficient operation, a metal clip is attached to one edge of the slide. These clips are supplied with the tray only. Trays currently in stock are new. Available only in very limited quantities.