This is a lens holder for a 52mm, 10x macro camera lens. It is designed to be strapped around a Reolink Argus Pro camera, with a velcro tie or similar strap. It fits the "KnightX 52MM professional macro 10+ lens CPL for iphone 11 phone Camera " (https://s.click.aliexpress.com/e/_oFTzoTT) lens very well in my experience, and allows the Reolink camera to take close up macro images when paired with a custom DIY bird feeder. Youtube instructions: https://youtu.be/IycyjnRZJlo