That R indicates the lamp can produce harmful UV radiations if the envelope is shattered. I have a 400W /DX lamp with a T on it instead of the R, the T meaning the lamp shuts off if the bulb shatters.
Looks just like my /DX...but the /N colour is great. I have a pair of Sylvania /N's in the 100w size, one medium & one mogul. Fantastic colour...very close to incandescent or warm CFL.
This lamp was from Colorado I bet, I went and picked mine up from their little shop thing. They are still selling them? O.o I thought I got the last one.
does it have the pinkish color when fully lit like modern sylvania lamps? my BT37 lamp from 1990 has the pinkish glow. so i guess even the non-chinese lamps had the pinkish phosphor at one time. The CRI is the best I've ever seen with mercs but the pink color is not something i like very much lol.
The N is for natural,it has a warmer tone than the DX lamps.Not sure if the N lamps are still being made,maybe EYE Iwasaki has N lamps still available.