The M113 has been updated with serrated, holed, comparatively thin metal sheet add-on armor. Is this just to protect against small-arms fire, or even against 12.7mm NSVT? Example: (I suppose that the effect is similar to the Leo 1A5's Deisenroth add-on armor to protect the turret flanks and hull against lateral 30mm AP shots, just for smaller calibers).