A telescope mount, like any other precision instrument, is inspected and tested before going on the market to certify it is working correctly. The parameter to be assessed is the periodic error. As everybody knows, the periodic error occurs in all mounts and it is due to several factors relating to their constructure.
All our mounts are tested inside our Laboratory at a constant temperature by sophisticated instruments which can record errors with 1/4 arcsecond accuracy.
It is obviously possible to test a mount directly on the field but the Laboratory conditions can guarantee more reliable values as too many factors, such as the seeing, could influence a test done outside compromising the final result.
Each mount sold by Officina Meccanica Bellincioni comes with a signed document reporting the value of the periodic error measured during the test.