This Beseler Universal Anti-Newton Negative Carrier is used for working with up to 6 x 9 medium format film stock. It is a round sandwich-style glass rotating type made for the Beseler 23C series enlargers.

Newton rings appear when two pieces of glass are sandwiched together with air trapped between them. If one glass surface is convex, this phenomenon will be more pronounced. Newton Rings will appear as a series of concentric circles. The light passing through the negative carrier experiences "obstruction" from the air inside and, consequently the rings are formed.