They’re better than jammers
"I swim in the sea daily during summer, and in winter I switch to the local council pool. Moving to fresh water is always a struggle, and the change in buoyancy is surprising. These do help, though it’s hard to know by how much. In my case, I feel I should have spent a bit more and gone for the Neoprene Buoyancy Shorts ‘Originals’ 5/3mm. I’m around 95 kg and could have used a bit more lift."