This part of ISO 11106 specifies the essential dimensions of a straight slide tray, open type (European design), for projector slides of the preferred international nominal size 5 cm × 5 cm complying with ISO 1755, with a capacity of 36 slides or 50 slides. It includes a testing gauge for checking the tray profile and gear system. In this design, the slide tray is placed upright into the projector and the slides are lifted approximately 9 mm out of the tray and then pushed sideways into the projector. Slides remain fully accessible when the tray is inserted in the projector and can be removed and reinserted. This part of ISO 11106 is intended to facilitate the manufacture, use and interchangeability of straight slide trays in different slide projectors which are designed for this type of tray.