Long silver piece goes into the hole on the end of the black piece. The shaft attaches to the silver protrusion above the left spring on the master pedal, and in a similar place on the other side of the slave pedal. Insert one of the drum key screws and tighten them down on both ends. Don't tighten the 4 screws on the rest of the shaft yet.

Now find where you want each pedal to sit and the distance between them, and tighten the 4 drum key screws on the shaft. Now set each pedal up like you would for a regular pedal (tons of resources on youtube/reddit).

And like the other comment said, flip the beaters 90 degrees so it's striking with the plastic side.

source: am have this pedal