For 45 x 107mm glass slides. Certainly the smallest and probably the simplest of the magazine type stereo viewers, since there are few moving parts. The top of the viewer holds twenty four slides, the side knobs allow one slide to fall into the viewing position, while the previous slide drops to the storage position below. The wheel between the lenses adjusts the focus. There appears to be a retailer's label missing from just below the ivorine label. Overall very good to excellent condition. Measures 5.75" x 4.75" x 6.5" high. A group of ten slides is included with the lot. Refer Wing, page 190 for illustrations and more information of the "Minimus".