Soma's CNC'd chromoly track cog, available only in black.  This is an ideal choice for those of you that are budget conscious.  We have these available in a wide size range, from 12 - 21 teeth. 

D'OH! Sorry Brahs, 12 tooth cog not available in 3/32"

Don't just take my word for it.  The people in the picture say it's O.K.