It's an expander!

A common appliance I use is an orthodontic expander, also called a spacer. These expanders widen the dental arches to correct cross-bites and create space for teeth. Some other benefits include potentially increasing airway volume and better sleep. We use conventional expanders on patients as young as 6 years old and up to 16 years old prior to the completion of puberty. Once puberty is complete, expansion can be accomplished but would require some extra steps. If you find that your child is grinding their teeth because they can’t “find their bite” or see crowding, an expander could be beneficial.