What material are the breastshells made out of? 

TheraShell backings are made of soft, flexible silicone backs and include both backings for sore and inverted nipples.  The domes are made of polypropylene. 

SoftShells are sold with only one type of backing, either sore or inverted. The SoftShell backings are also made of soft, flexible silicone backs, but have a more flattering contour under your clothing. 

How do I use breastshells?

Only wear breastshells during waking hours.  The reason that you would only wear them during the day is so that you do not have to worry about lying on them or having them shift.  If they shift they could apply pressure to the wrong area. If you are awake, you will know if they have moved out of place or if the pressure is too much and be able to adjust them.

If using the SoftShells, do not feed the milk collected in the foam insert to the baby.  Discard this milk.

For inverted nipples, begin wearing the breast shells during the last couple of weeks of pregnancy (contact your healthcare provider before pre-natal use).  Continue to wear them after the baby is born between feedings, until your baby latches on to the breast without difficulty.

For sore nipples, breast shells can be worn continuously between breastfeeding sessions.