Bought these for my pregnancy based on a tip from a recently pregnant friend.  Total gamechanger.  Only had to buy a new sized bra once, and then used these for the rest of my pregnancy, as my cup size didn't change any more but omg my ribcage just kept on expanding and expanding to accommodate baby.  IMO, these make wearing a regular bra possible during those body-changing portions of pregnancy,  saving me money in the long run.  Additionally, they work as expected...they clip onto the original spacers easily, they match up with the original hooks really well, and they are very comfortable and easy to use.

Best $6 I've ever spent on Amazon.  Buy them, you won't regret it.