M4R is an extension characteristic of files used in Apple mobile devices. M4R files are audio storage files used as notification tones and ringtones on the device. These files are generated from AAC (M4A) audio files available from the iTunes Music Store. The ringtone in M4R format can be up to 40 seconds long.

M4R are ringtones mainly made in iTunes, but there are other software that can do this.