Baking Cups, CupCake Liners and Candy Cups come in a very wide variety of sizes and colors. It really depends upon what your usage is for what size and color you wish.
For a general idea on how they are used:
Standard Cup Cake size liner is: 2 inch base with a 1-1/4 wall height.
#4F is: 15/16 Base with a 11/16 wall height
#4SP is: 1 inch base with a 3/4 inch wall height
#5C is: 1-1/8 Base with a 13/16 wall height
#5A is: 1-1/4 Base with a 3/4 wall height
#6 is: 1-1/4 base with a 7/8 wall height
#601 is: 1-3/4 base with a 5/8 wall height
#8 is 1-1/4 base with a 1 inch wall height
#9SPD is: 1-1/2 base with a 1 inch wall height
#9 is: 1-1/2 base with a 1-1/8 wall height
#9D is: 1-3/4 base with a 1 Inch wall height.
Some of the listed cups are only available in bulk sizes, special discounts apply for these items.