Hello, there are 3 different versions. Each comes from a different manufacturer and is based on their rail system. The outer shape is essentially always the same and corresponds to the Blum Tandembox plus. Accordingly, the Blum drawers were available everywhere first. In 2007, the second version from Hettich came, which has since been sold (was sold) in Northwest Europe. In the remaining countries, the Blum version continued to be available. However, these have only been sold in North America and the Pacific region since the beginning of the year. Newly added is the Italian manufacturer Manuex, who now supplies the drawers for Southern and Eastern Europe as well as the Middle East. Except for the Rationell drawers for non-metric North America, every version can be used in Faktum cabinets. It should also be noted that not every carcass rail of the Blum version can be equipped with a damper. That only came in 2006. The very early version was also only a partial extension, but as far as I know, it was not available for the 30 cm wide cabinet.