I'm planning to sell 4 disk that I still have but don't use.

For the magnetic disks I have used the following command:
sudo dd if=/dev/urandom of=/dev/sdb
This worked excellent.

Now, how to use the "dd" command for an SSD (Kingston 64GB ssdnow v series)

Should I use the same command or add somthing like blocksize and stuff like that.

Thanks!

There was a recent academic paper on the difficulties of fully erasing an SSD, due to effects of the FTL functionality. You can try Googling if you want to read it.

My "takeaway" from that research was that it was more effective (though in some cases, still not perfect), to use the Secure Erase function in the SSD firmware instead.

Therefore if I was in your situation with an SSD, that is what I would research (i.e. check whether your Kingston drive supports the Secure Erase command) instead of using just a dd overwrite.

parted magic distro, has a nice HDD eraser, it might have the secure erase for your SSD. its worth a shot, & might be eraser that trying to DD the drive, download the ISO, Burn, Boot the Distro & see if it shows up