It would be important to include detailed instructions for use with the collimator, because this device is not self-explanatory. Also information, what can be done with it.
This is beneficial for interested parties who have no experience with it and thus increases the potential customer base.
There are three key PDF on the learn camera repair site that describe in detail the function and use of autocollimators for camera repair.
1) Camera Craftsman May-June 1978 (best)
2) Nationa Camera Instruction Manual for Auto-Collimators (two versions; very similar).