difference between 500 and 500n ESL/Sentrol smokes

[Rex Wilson]

Anybody know the difference between the ESL (Sentrol) 500 series and
the 500N series?
The Sentrol literature defines the "N" as "new style", but doesn't say
what that means. Is this simply a cosmetic/external style change? Or
are there actual improvements to the device?
thanks.

 

[Taz]

Doesn't seem to matter much. As I understand it all the 500 series have been
recalled.... Anyone else..?