This is Waterproof’s pair of Xlite Replacement Drysuit Boots. The updated Xlite boot has a narrower fit, which makes donning of the fins a lot easier. They are also less buoyant, making the drysuit really easy to dive, since you are not risking your feet constantly floating up (at least not because of the drysuit boot itself).

The Waterproof Xlite Dry Replacement Drysuit Boots have to be attached to your drysuit by a professional.