A digital drum machine produced by Alesis, beginning in 1990. The SR-16 was one of the first low-priced digital drum machines, and so was affordable to many musicians who couldn't afford a high-end digital machine from E-mu or Linn. It came loaded with 233 drum and percussion samples, some of which were multi-sampled. Pattern memory held 100 songs with a total capacity of about 12,000 notes.
Despite getting mixed ratings from reviewers (many of whom were uninspired by the samples), the SR-16 has proved to be one of the most popular drum machines ever produced. Alesis kept it in regular production for at least 20 years -- it is unknown exactly when production ended (as of 2017, it's listed as a "legacy product" on Alesis' Web site), but enough were produced so that new ones are still available in 2017.