It's just cause the finish is different. It's a thicker steal than the other bodies. I have a V5 Stailess. And I can tell you first hand three important factors with the
device...
1) Don't drop it. Mine fell less then a foot onto a hard wood floor and the bottom cap threads bent and very hard to remove now to use in 18350 mode. It'sd a backup now so I don't care.
2) Don't push the button hard. My adjustments button after about a month are uneven and the left button is sunken in considerably. I have read it is a problem with the board inside twisting, but since it's a backup again I don't care anymore.
3) Don't drop it.
Ok here's a fourth. Make sure it is in RMS mode as if not the flavor will taste like burnt *&^.
I guess really I had five. Get something else if this is your only mod. You will definitely want a backup because while it is a great short term device, i found mine personally to be junk.