SauRoNZA
Honorary Master
Its a pine box with a sheet of thin wood(now plastic board) on to, stapled in... thats it, nothing else... only 'circulation' it gives is after you accidentilly put you're foot through it when rotating mattress![]()
The bases generally aren’t solid and also slatted inside and with wider gaps but layered with that plastic sack material which does breathe.
Depends from one mattress to another obviously. Some will even have a warning on that they are made for a slatted bed only etc.