Model M's in Scotland until 1999. Maxi Switch purchased assets for rubber-dome keyboards and the Lexmark Select-Ease Keyboard (model M15), including a buckling-spring switch patent. They continued to manufacture the IBM Enhanced Keyboard with TrackPoint II (model M13) in Mexico until 1998. Some of Lexmark's keyboard manufacturing assets were also sold to a group of Lexmark employees, who formed Unicomp whose basic version of the Model M was similar to part number 42H1292, first renamed 42H1292U and later the Customizer. There have been other configurations, including updated 104- and 105-key layouts; a Unix layout (where the Ctrl and Caps Lock keys and Esc and tilde keys are transposed); models with integrated pointing sticks and trackballs; and POS-specific models such as those with built-in magstripe readers. All used the press-fit controller characteristic of late Lexmarks. Unicomp continued to use the original IBM machinery to produce Model Ms, leading to a gradual decline in quality as the tooling became worn. This, and various problems with their USB controllers helped keep a market for vintage Model Ms thriving. In 2020 Unicomp replaced its tooling and shipped a "New Model M" with noticeably improved build quality that more closely resembles the classic 1391401 (though with a 104- or 103-key layout and USB); many older variants are no longer sold on Unicomp's website and some still on sale have been deprecated. Variations The Model M's numerous variations (referred to as "part numbers") incorporated alternative features and/or colors. One of the more sought after variants of the Model M keyboard is the Space Saving Keyboard, which integrates the number pad into the keyboard's main section, substantially reducing its width. The Space Saving Keyboard is likely the origin of the keyboard layout that is generally known as a "tenkeyless keyboard". IBM released the standard and Space Saving Model M's in an alternative 'gray/pebble' color for use with their Industrial computers, designed to conceal discoloration from handling in production environments. Other variable features include a grounded spacebar and, on some later models, drainage holes to deter damage from spilled liquids. The M2 was a late Lexmark variation issued under cost pressure from competing rubber-dome keyboards. Some revisions used rubber-dome switches; others retained buckling springs. All had a much thinner, lighter case and discarded the metal backplate. It can easily be distinguished from the original Model M design by its flat, unsculpted front case section; also the manufacturing label,