Awesome Thanks!Check this diagram:
2013 Kawasaki NINJA 300 (EX300ADF) Side Covers/Chain Cover (Adf-Aef) | Babbitts Kawasaki Partshouse
From what I can see, those pieces are referred as Cover Seat. The code is 53065 followed by a letter that identifies each particular piece (side, tail or center), side of the bike (right or left) and the color.
For example, for my bike, which is a 2013,
what you marked as 1 would be the Cover Seat Tail, RH, EB (Color ebony), code 53065L
and what you marked as 2 would be Cover Seat Side, RH, EB, code 53065B
Check the diagram for you year make of your bike and identify what color is your bike.