What do these numbers on the top of these mini linear actuators denote? I'm building 42082 and there are 4 of these but 3 unique numbers in the tops.


20X8 on two
29X8 on one
35X8 on another


I'm guessing they are serial numbers from machines that made them but I wondered if someone had a better idea.
First two digits represent week of production followed by a year.

20X8 - 20th week of 2018.

These codes used for quality control. LEGO Customer Service may ask you to provide this number if there were an issue with a set or particular part.

Similar code exist on box seals too.