These targets can be used in SM05 optics components to help align lasers.
4 parts have through holes to pass the laser beam through, and 4 parts have no hole, so you can see where the laser beam aligns on the optics component.
Here is an example of some beam splitter cubes it would work for:
https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=7469&pn=CCM5-PBS204
Parts are easily installed and removed in the lens mount holes. They are held in place by a snap fit.
Use a pair of diagonal cutters to seperate the individual parts from the set.