This is a scope level. It shouldn't work but it does.

Attach the device to your scope with a rubber band. Make sure the long part is referencing on the barrel.

Turn your scope power to its lower setting. You shouldn't be able to see the reticle but you can. My 4-16x Vortex works fine with this on 4x.

Set the rifle on a rest and pivot it until the bubble shows level. Have a horizontal line downrange. It HAS to be level for this to work. When you have the reticle parallel with this line –and the bubble is in the middle –torque the scope mount screws.

I used an M4 16 machine screw to hold the parts together. Depending on what mood your printer is in, you may have to touch the parts up with a file.

Glue the spirit bubble to the device with super glue. Attach it before you attach the two pieces.

I bought my spirit level here: https://www.amazon.com/gp/product/B07VTQG17V/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1