=IF(D8<=150,"SR250",IF(D8<=350,"SR475","25x3"))


Using < > doesn't work in formulas because it will test the first assignment of If 350<D8 and return a True or False value, then it will check to see if True/False>150.


Setting up the formula like I did above, it will check each instance... If it's <= 150 then "SR250" and if that is false, it will check to see if it's <= 350. If it is then it will give you SR475, if not then it will just return "25x3"