This is it, it's a thing for kids (or short people) to hold the belt off the neck out of the way and lock them in place.

https://www.amazon.com/Diono-Secure-Proper-Reinforced-Silver/dp/B005PK1D1A/ref=asc_df_B005PK1D1A

https://www.youtube.com/watch?v=k7YTlwh3Mos