LEGO Red Streamer Flag 4 x 1 with Right Wave has been used in at least 187 LEGO sets over the past 40 years, since it was first used in 1984. You can also find this part in at least 35 other colours. It has a design ID of 4495 which can usually be found molded into the bottom of the part.
Lego 4495b streamer flag with Right wave (x1) more colours than shown
LEGO People Pack - Fun at the Beach Set 60153 Inventory
LEGO The Ostrich Race Set 7570 Inventory
LEGO Black Streamer Flag 4 x 1 with Right Wave (4495) Comes In
LEGO Blue Streamer Flag 4 x 1 with Right Wave (4495) Comes In
LEGO Parts - Latest Editions – DASHBRICK
LEGO Bat Lord's Catapult Set 6027 Inventory
LEGO Super Heroes Magnet Set (853431) Inventory
LEGO Night Lord's Castle Set 6097 Inventory