The IBM Space Saver Keyboard with TrackPoint II was a variant of the original Model M4 that featured an integrated TrackPoint II pointing stick. The Model M4-1 is notable for being the first IBM desktop keyboard to feature TrackPoint technology and the only Model M to retain a strain gauge-based pointing stick after Unicomp took over production. Unicomp's internal code name for the M4-1 was "Surf".