Re: diameter of mono line ?
Very hard if you do not know the brand. As an example trileen xl 40 lb or magnathin 40 and p line 40 are about .022 but k mart bulk line is about .030. I disagree with most that say line goes bad and needs replaced very often, but you must keep it cool and out of sun light. The spring guage and pull till it breaks will work pretty well with any IFGA line but the cheap bulk lines like K mart sell will usually break at a higher weight. Like the 40 will break at 50. If you are putting it on your best rod for big fish I agree with JB, DON'T DO IT. Most 8 lb are about.008.
