They'll hold maybe 2 clutches, in separate containers. They hold heat fine.
I was very unimpressed, because they don't hold humidity worth a darn, which means the eggs MUST be in separate containers.
A Hovabator, which is the same size, can hold 5 clutches of ball eggs in a substrateless setup, without separate containers, so that's what I use. Hovabator + thermostat is around the same price as the Reptibator.