Desert Boot - Black - size 7, size 8, size 9 -  2 pairs each

Desert Boot - Pink - size 8, size 9 - 5 pairs each

Desert Boot - Red - size 4 - 10 pairs

I only have one product (Desert Boot) but there are 3 different colors, and sizes from 4 to 12, so that's a lot of variations.

How do I enter this into Zoho CRM?

Do I enter every single possibility of every single product combination into my products list?

(and therefore give each item a unique SKU)

Do I just enter by product name, and make custom fields (drop down menus) for the variations?

What is the "proper" way to do it- and can I please hear your advice. I want to sort this out before I start entering the data and processing orders.

Thanks!