I know that the "S" is generally more desirable. I have two 28-2s. A 4" "N" serial number and a 6" "S" serial number. I'm thinking about thinning the herd a little bit and may sell one. If the 4" was the "S", the decision would be easy. That's the one I'd keep. I just like 4" guns over 6" in a .357. But, it's the other way around. The 4" is the "N". Don't really need to sell either one. Kind of like having both. Honestly, they're both safe queens. Owned them for years and haven't shot either one.