The earliest Leica reflex housing was the PLOOT (Leitz's five letter code for its products), announced in 1935, along with the 200 mm Telyt Lens. This date is significant because that it places Leica among the 35 mm SLR pioneers. Moreover, until the 1964 introduction of the Leicaflex, the PLOOT and Visoflex were Leica's only SLR offerings. A redesigned PLOOT was introduced by Leica in 1951 as the Visoflex I. This was followed by a much more compact Visoflex II in 1960 (which was the only Visoflex version available in both LTM (screwmount) and M-bayonet) and the Visoflex III with instant-return mirror in 1964. Leica lenses for the Visoflex system included focal lengths of 65, 180 (rare), 200, 280, 400, 560, and 800mm. In addition, the optical groups of many rangefinder lenses could be removed, and attached to the Visoflex via a system of adapters. The Visoflex system was discontinued in 1984.