This information emerged while researching a video on the rOtring 300. It seems that, apart from the 2mm model, the line was discontinued for some time after Sanford-Newell’s acquisition in 1998. Then brought back around the time that they resurrected the 600. (maybe a little earlier?)
The first column lists my sources—either catalogs I’ve found (and shared here) or those verified by fellow collectors (Bjorn and Dux). Some were cross-checked using the Internet Archive.
My research indicates that the rOtring 300 underwent a manufacturing change at some point, with a hole added to the eraser cap to address a choking hazard. While the exact date of this change isn’t clear, ISO 11540 published in 1993, sets safety standards for caps on writing and marking instruments to reduce asphyxiation risks, especially for children under 14. If you own a rOtring 300 with an eraser cap lacking a hole, it’s likely an early model—congratulations!
I’d love to hear from anyone with additional details to share on this topic!
Looks like the standard was released in 1993. then updated in 2014 and 2021.