Which SR Blue or black Fuse

Which SR Blue fuse for ARC REF 5SE? It says 5A slo/blo 250V on the fuse but no size MM?any help? Anyone had any experience with either fuse and what was the result.
Thanks @geoffkait  @mental 
Fuses, fuse holders and the additional wiring ( or circuit board traces ), impair the sq, but, for the protection of the piece of equipment, it is there. One comment I always appreciated was by Bill Lowe of AQ.    " To Due Less Harm ". Better fuses ! Enjoy! MrD.
Remove all the screws from your gear, and replace them with titanium versions. Your gear will sound that same, but it will be slightly lighter, possibly resulting in the .0000023% sonic improvement attributed to fuse direction. I did say "possibly" but sonic enhancement from a fuse is mythological at best, and expensive at worst.
But what if you already have a screw loose?
Too have a screw loose one is making a dangerous assumption that there were any screws present to begin with......