Summary

This is an adapter for a Laser Bore Sight tool to be used in a 50 BMG

https://www.amazon.com/gp/product/B09JBMT9MD?ie=UTF8&th=1&linkCode=sl1&tag=flyingrich-20&linkId=c24774475a5d6d0e19c0b419e30d3b6a&language=en_US&ref_=as_li_ss_tl

I have a YouTube video on how to use it. https://youtu.be/P_DIvtOJURI

It is printed on an Ender 3 with PLA