06B-2 hub sprockets have two tooth rims and work with duplex 06B-2 chain of 3/8" (9.525 mm) pitch to DIN 8187 / ISO 606. They let you transmit more power without increasing the chain pitch.
06B-2 duplex hub sprockets - a stronger drive in a compact installation
A duplex drive is a way to strengthen a machine without rebuilding it for a larger chain: you keep the small pitch, quiet running and compact installation. You bore out the pilot bore for your shaft, and larger sprockets can be chosen in grey cast iron, which dampens vibration well.
06B-2 hub sprockets in C45 steel and larger ones in grey cast iron
06B-2 duplex hub sprockets in C45 steel with unhardened teeth, and larger grey cast iron sprockets. For high-speed drives it is worth considering sprockets with hardened teeth from the Hardened hub sprockets group.
Replacing both sprockets when moving to 06B-2 - questions and answers
Do both sprockets have to be replaced when moving to a duplex chain?
Yes. Both drive sprockets must have the same number of strands as the chain - you replace the driving and driven sprockets with duplex ones.