Two capacitor sets are included, as pictured. I use these often for antenna coupling and/or fine tuning, in crystal radios and regenerative receiver projects. With both 20pf sections in parallel you get 40pf total.  

The shaft size is approximately 5/8ths inches and will work with 1/4" dials knobs.  Just the right size for most applications. This item comes with a control knobs and scales, as pictured.

Shipping to the United States only.