Super easy for reticle alignment, faster than feeler gauges - only 2 caveats - Arisaka Defense Combo Optic Levelers

These make reticle alignment super easy and fast. However, there are 2 caveats I feel you should be aware:

The biggest one is that it all depends on if your mounting platform is machined true, and if the scope tube is machined properly with the reticle aligned properly to the scope tube. On a quality setup, this should be fine. I'm talking like Japanese glass Vortex scopes (Razor) with a quality Picatinny rail that is in-spec.

The second caveat is if your scope turret/body size to rail clearance may not allow for this leveler to work. I only ran into this in a few situations. In that situation I had to use feeler gauges.