Thank you for viewing! These are safety parts for baby gates. When you insert them where you attach the baby gate, the friction makes it much stronger and less likely to slip. It's easy and recommended, as you just sandwich them between the wall and the gate (´∀｀) They are made of plastic and rubber. I only used two out of the set of four, so these two are opened but unused. I will ship via anonymous delivery, so please rest assured (^^)