PetSD by Nils Eilers. This is a much better design that uses proper IEEE-488 bus drivers to connect to the Pet, so should co-exist happily with real Commodore disk drives.
NODISKEMU, and that is the firmware that is running on the pet microSD. It is compatible with the original petSD firmware as well, but the new code is recommended. This firmware is still under development, and can be updated as new versions are released by placing the update files on a microSD card - no programmers are required. There are various new products soon to be available in the world of pet disk drives. Dave Stevenson has a useful comparison matrix.
Please contact me if you would like to order one of these.
I've now written a pet microSD user guide.
pet microSD boards, in blue, also include a datasette power connector with passthrough.
Update 3 :
different models of PET, including internal mount. That link has buy it now buttons.