These are super thin disposable liners that can be placed on top of any diaper. When your baby poops, you can simply lift off the liner and flush it and the poop in the toilet. These make an easy transition to cloth diapering and will keep your diapers from staining. There's no need to use these before starting solids, as primarily breast feed or bottle feed baby's poop is so runny it just soaks right into the diaper. Besides using these to remove poop, they can be used to protect your diapers from any non cloth diaper safe creams that you may have to use from time to time.
Bio Liners are also loved by daycare providers!