Theyre basically implant sizers that u can make at home. U get a pair of really thin tights (I used pop socks), cut off the two feet sections, fill them with raw rice in grams to the cc amount. So in your case, fill each one with 300 grams of rice, as that is the difference in cc’s that you’ll be having. Tie the ends, and you’ll have two makeshift 300cc implants. Shove ’em in your bra, and it gives u an idea of what size the implants will be. (Google “rice sizers” to get a better explanation).
I had 550cc from a really flat chest, and think I’m gonna be a DD, or E at the most. I’ve got pics on my profile page, so feel free to have a look. I’m only 9 days post op, so have some dropping and fluffing to do, but they aren’t as huge as you imagine!