Well, for mink the number one longspring would be fine, a 1 1/2 would be better though to provide weight for drowing sets. Drowing sets should be utilized for mink. Some trappers use up to a number 2 coil or longspring but for these larger sizes the catch is high and will dispatch mink. So a number 1 would be ok, lighter to tote and less expensive to lose to high water or trapline theives. My favorite foothold mink trap is a 1.5 coil/longspring though. Montana Hunter