No I'm not. 18650 is the size, NCR1850B is a very specific model of off-the-shelf cell in that size manufactured by Panasonic with a specific chemistry and spec

No I'm not. 18650 is the size, NCR1850B is a very specific model of off-the-shelf cell in that size manufactured by Panasonic with a specific chemistry and specification. As far as I can tell (it's not something the manufacturers release much information about publicly) the "NCR" part identifies the chemistry as Lithium Nickel Cobalt Aluminum Oxide.