The Hi-Lo stuff is regarding the operation of the fan. They send you some sort of switch that does something with the fan as far as running it in low or high speed.
FWIW the newer Kenne Bell stuff I have seen, while not near as advanced as stuff that the better chip guys are doing, isn't so bad. Problem is there is a LOT of the old stuff out there floating around. While these days that stuff is detonation city, you have to keep in mind that back in the day when these cars were new, gasoline was a lot better than it is now and you could get away with a lot more.