"Safety Stop" was formerly called "Instant Quarantine." Here is the review I wrote on the Marine Depot website a couple of years ago:
Not a Quarantine
Sustitute
by WILLIAM SCOTT
One Star
Unsatisfactory
..............
Well there you have it. I heard of this from some online retailer that had it as an add-on option in the shopping cart when you bought fish. I didn't get it.
One other thing I just thought of that might be an option for the OP is TTM (Tank Transfer Method), not sure if anyone mentioned that yet. Now this I have used with every Tang I've gotten since it is geared towards Ich mostly. I also did the optional Prazi step as part of it. In those cases I did not do a full quarantine, only the TTM. It really requires very little to do. My TTM setup is two 5 gallon tanks I got from Petco during one of their $1 per gallon sales, 2 HOB filters for circulation (no media), 2 small cheap heaters, and a bottle of Prime. I got 2 of everything so I can let one entire set dry completely for > 24 hours before it's used again. I think the entire cost was like $50. Here is the article/post about it... https://www.reef2reef.com/threads/tank-transfer-method.192655/
EDIT: By the way, all that stuff only needs to be out temporarily when you get a new fish. Otherwise it can be tucked away in a closet or cabinet the rest of the time.