A Fuse question


I just purchased a Magnum Dynalab Integrated Amp model #MD 308
I always check fuses for correct value before using.
This unit states on the back "3AG fuse " however it does not state the amperage
The fuse that is in it says : 250 v.... 4A
I checked manual to verify the correct fuse amperage is in it ( 4 amp ? ).....but manual does not 
indicate amperage!
Does anyone have this info I am seeking. 
Perhaps an owner of this amp could check and verify for me.
Thank you 
rocky1313
Imhififan is correct in that, "3AG" only represents the fuse’s physical size/material.   Nothing to do with electrical specs (ie: amperage, voltage or time characteristics).          "AG" is actually short for, "Automobile Glass", and, "AB": either Bakelite, fiberglass or ceramic.        https://www.littelfuse.com/~/media/electronics/application_guides/littelfuse_fuseology_application_g...        Contacting Magnum Dynalab is your best recourse:       http://www.magnumdynalab.com/contact/
" 3AG fuse " is a size of Ø 1/4" X 1-1/4" length glass fuse, it available in fast acting or slow blow with different voltage/amp rating.

https://www.parts-express.com/littelfuse-4a-3ag-slow-blow-fuse-5-pcs--071-704

FYI, if you want a ceramic fuse, look for " 3AB fuse " instead.
If it is 3amp and doesn't blow, then it's going to protect better than a 4amp one will.

Cheers George
3AG is a 3 amp slow blow fuse.

4A is probably a fast blow. Single wire or one coiled around the other, kinda looks like a spring... That is a slow blow..

The straight wire fast action fuse..

Regards