Many of these Boot Images were used to create bootable thumb drives using the dd command.
The Ubuntu Desktop thumb drives were created with the Startup Disk Creator, which will reportedly work with any debian-based iso.
The PNY drives are USB 2.0. The rest are USB 3.0, which might be preferred.
SystemRescue running on an older MacBook:
Darik's Boot and Nuke on Sourceforge.net
Image, instructions, and other information, here.
This is deprecated. It did the job, let's see if we prefer one of the SystemRescue options, in the future. By default, this image boots using a different keyboard layout, possibly in Finnish. It is recommended to get things reconfigured to the appropriate locale settings before attempting nwipe.
Note: Parted Magic is not free. John purchased a license for the sole purpose of wiping SSDs. It is an interesting product, and licenses start at $11.
This is an interesting article on SSDs. You might skim it. It recommends Parted Magic and also provides other possibilities.