My nice laminated ones are still at school, so you will have to do with this one straight out of the printer and use your imagination. So basically there are two wheels with 12 pie pieces each (I usually have 24 students). Layer them and use a brass fastener to attach them in the center of the wheel so that both wheels can turn freely.
The most basic way to use these is to write the names of any students you DO NOT want to be working together on the same wheel (he he). To find partners, simply turn the wheels until the names line up. In 5 years of using this, the students have never figured out that they won't be able to be partners with students on the same wheel as them (he he he).
I usually make multiple wheels. I like to make one for reading with higher readers paired with lower readers for certain activities. I print them on cardstock, laminate them, and write the names with overhead marker so I can erase and change names as students come and go.