Looking at the T8 4 bulb 8 foot Metalx fixtures at menards. What do I want? They list two similar lights 8TSNF232 and the other is the same but with an R at he end of the model number. Is the R reprsenting a "residential" ballast and the other maybe commercial? And also, are these Metalux quality lights? Was looking at Lithonia at HD but with menards 11% I can save qute a bit. I was thinking 21 for a 38 x 52 with 12.5 ft ceiling. White liner tin on ceiling and walls.