Hull Zinc Compatibility

[Weatherbird]

I ordered some new hull zincs for my boat and while the hole pattern is the same, the plate that the bolts go through on the old zincs is flush with the bottom of the zinc where on the new zincs, the plate is recessed.

It seems to me that the new zincs will only make contact to the conductor on the boat with sacrificial material that once gone will leave the zinc loose and out of contact.

Am I misunderstanding the situation? Should I be looking for some type of conductive spacers to install before the zincs? Do I just need to find the other style of zinc?

There doesn't appear to be a way to differentiate between the two types online. They're both sold as ZHC-3 and the website I received the new zincs from has an image matching the original zincs.

Photos: The shinny upper zinc is the new one and the lower is the old one with the plate flush with the back of the zinc.