All Synths, Samplers, Sequencers etc.Beside drum machines and guitar products Roland is famous for synthesizers. Their excellent sound is one of the reasons of Roland being famous among musicians and you will hear preset sounds from Roland synths in many top hits.
Roland invented the pitchbender (SH-5,1975), separated MIDI-soundsources from the keyboard (MKB-300, MKB-1000, MKS-10 und MKS-30; 1984), built the first multi-timbral MIDI-Synthesizer with drum sounds (MKS-7, 1986), integrated as first effects within sound synthesis and used PCM-Samples as waveforms for a standard synthesizer oscillator (beides D-50, 1986).
Roland sequencers of the MC seriec are famous for their excellent timing and groove. The first concept of a GrooveBox was also from Roland (MC-303, 1996).