to effectively lengthen the stereo base for scenic shots and reduce it for macro shots, but these were seldom used. Accessories and mounting services Because the Realist effectively created a new format of slide, its users needed a new line of accessories and services. The David White company obliged by producing a whole system which included everything needed to take, mount, view, and store stereo slides. Among the available accessories was a complete mounting kit which included a sorting tray, film cutter, tweezers, three different types of aluminum masks, cardboard folders, a mounting jig, and mounting glass. Mounting glass could be secured with mounting tape, binder frames, or with plastic "Permamounts". Permamounts were considered premium mounts, with a label on one side and a neat viewing window on the other. They were considered suitable for projection because the rigid plastic construction was stiff enough for automatic magazines but no plastic covered the image area so there was no interference with polarization. The operator of the projector did need to be careful not to leave the same slide in the projector for too long, because the heat would eventually start to warp the mount. Viewing accessories included several types of slide viewers, the Realist stereo projector, and polarized glasses. There were various types of slide storage cases available, some of which could accommodate the viewer as well. Most of these accessories were also made by other companies, which sometimes improved upon the Realist offerings. The stereo projectors made by TDC (Three Dimension Company), for example, were far more popular than the Realist stereo projector. Some users preferred cardboard slip-in mounts made by third parties because of their ease of use, even though they were generally considered to be of lower quality and were not suitable for projection. The Brumberger binder frames and mounting glass were very popular among users of stereo projectors. All of these can be found on eBay in used or occasionally NOS condition and some of them (or their modern equivalents) are still manufactured. The Realist stereo mounting service used several different types of mounts during its run. The earliest mounts used a type of aluminized cardboard mask inside a cardboard foldover. This tended to warp with exposure to humidity, changing the alignment of the film chips. In older slide collections, the film chips may have slipped to the point that the slide is unviewable without readjustment, and