The packaging of the bar is quite minimalist (I'm assuming OEM), but absolutely OK. The installation in the iMac went quite quickly. Power cord, decreased memory door, put the bolt in the two free slots, cover again and power cables off. Took less than 5 minutes. iMac on again and he sat up without problems, now stop with 24 GB RAM. I then also again a hardware test carried out by the ran without an error message.
Conclusion: I would highly recommend for the Mac the SAMSUNG PC3L memory entirely, even in mixed operation, there seems to be no problems.