This is a mount for two different styles of UV flashlights. These flashlights are sold under several different names. The links below are to the amazon pages of the ones I used to create the model.

ALONEFIRE H42UV 36W 365nm UV Flashlight: https://www.amazon.com/dp/B08RHTN7RV?psc=1&ref=ppx_yo2ov_dt_b_product_details

uvBeast New V3 365nm Black Light UV Flashlight: https://www.amazon.com/dp/B01CV1XW5K?psc=1&ref=ppx_yo2ov_dt_b_product_details

The mount also supports a 15W round excimer lamp.

The project is documented here: https://www.instructables.com/Build-a-Simple-UV-Photography-Box/