New to Archive-X is mini sets, this is a way of purchasing sets for multiple subjects without purchasing every full set 

Set Y

Used specifically for Y-Wing and many more 

Contains

AX-021 1975 SP Armour Yellow 

AX-023 1975 Reefer orange

AX-014 1975 Mud

AX-005 1975 Dark Reefer Grey 

AX-036 1975 Big Sky Blue 

For Example, if you wish to purchase paints to do most X and Y wings, you can save money by purchasing sets  1, 2, X, Y