Kodak also offered a stack loader that allowed running a stack of up to 40 slides without using a tray, but forward only; and clip sets holding up to 36 slides per clip. A box of 12 clips could store up to 432 slides, and keep them organized. During the 1970s, Kodak also produced a "Pocket Carousel" projector for use with miniature 110 format Kodachrome and Ektachrome slides. The Kodak Carousel projector was discontinued in October 2004. Less well-known but plentiful is a family of projectors based around a design originated by Sawyer's and later sold under other brand names. That manufacturer's first slide projectors, in the late 1950s, had used straight trays. In 1963, Sawyer's Rotomatic, the first version using circular trays (called Rototrays), was introduced. These are distinguished from Kodak Carousel projectors by the round tray being in an "upright" orientation, like a Ferris wheel. Unlike the Carousel tray's use of a locking collar to hold the slide in the tray, the Rototray held slides in place using friction and a metal spring against the side of each slide. Projectors using the 100-slide Rototray were backward-compatible with the TDC-Universal straight slide trays that had been popular since the late 1950s. The 1960s would also see the introduction of a plethora of less popular tray designs, most incompatible with each other, introduced by manufacturers possibly hoping to profit from the razor-and-blades business model. The first Kodak Carousel projector was targeted toward the consumer and carried the model designation '550'. In 1963, the first professionally oriented model was marketed in Germany as the Model S. Other models include:  The manufacturing date may be decoded using the CAMEROSITY code, which is a four or six-letter code which corresponds to the month and year (four-letter) or month, day, and year (six-letter) of manufacture, using the substitution cipher C=1, A=2, M=3, E=4, R=5, O=6, S=7, I=8, T=9, Y=0. The code is located either on a silver label inside the cord storage compartment or pressed into the plastic of the bottom-mounted cord wrap. The Kodak Carousel slide projector was part of the plot of the 2007 episode "The Wheel" in season 1 of the TV series "Mad Men". In the episode, the advertising agency comes up with the name "Carousel", in place of the Kodak executives' name for it, "The Wheel", pitching the device as a nostalgic conveyance that let its viewers travel through their memories as a child would, "around and around and back home again to a place where we know we are loved".