For alignment purposes, it is easy to set a good (Grade 5) steel ball on a lens post, but there are times
when a lens post is not a good option as a mount for an alignment ball. In this case, we offer ball/nest
pairs where the nest has a plane rear surface with a magnet suitable for placement on a ferromagnetic
surface or cemented to a non-magnetic surface. This ½” size pair is particularly useful for positioning the
nest with a laser tracker as the nest also accepts ½” ball-mounted retroreflectors (BMR or SMR). Each
nest is sold with a ½” Grade 5 ball.

Additional balls are available here.

Disclaimer: All specifications and prices are subject to change.