This part is an adapter that allows the PASCO Smart Cart to carry the PASCO Wireless Light sensor for studying the Inverse Square Law. The bracket raises the light sensor to align the sensor with the PASCO light source or color mixer.

https://www.pasco.com/prodCompare/smart-cart/index.cfm
https://www.pasco.com/prodCatalog/OS/OS-8470_basic-optics-light-source/