The fuses we use are as below…
0001.2508 Shurter Fuses
https://nz.element14.com/schurter/0001-2508/fuse-antisurge-ceramic-2-5a/dp/1360854
Hold the red connector the way you would in order to insert it into the receptacle.
On the right side the direction is from the back to the front. On the left side the direction is from the front to the back. This is true whether 115v or 230v. But in some countries you are wise to also try reversing the polarity of the power cord (EU for example and that is easy to do with a Schuko) because of how they separate the phases of their power delivery.