Pre-Folds are flat rectangular diapers with a thicker section down the middle- just like baby cloth diaper services provide.  They can take a bit of practice to put on, but unlike “contour” or “fitted” diapers, pre-folds can be securely fixed around the legs and waist, so floods can’t leak.  I use these gigantic pre-folds to contain the inevitable leaks that happen when I’m working on getting a thick layered disposable 100% soaked to capacity.