 The R series was introduced in 2009 with the YP-R0 and the YP-R1.The YP-R2 released in 2011 is the successor to the YP-R1 but the YP-R1 is not the successor to the YP-R0, which makes Samsung's naming scheme difficult to understand.The YP-S2 is a screen-less MP3 player shaped like a pebble with tactile buttons on its underside.