[j-nsp] PE-1GE-SX vs. PE-1GE-SX-B

[Markus]

Dear list,

maybe I'm not good at searching today, but I can't find any info at 
juniper.net and via Google on the difference between PE-1GE-SX and 
PE-1GE-SX-B. Can anyone shed some light on this? :)

Thanks!
Markus