This is a bit for cutting box joints in thin, narrow stock for tiny boxes and drawers. One pass cuts all the notches and tabs in the end of a piece 1-9⁄16" wide. Two passes (and a bit adjustment) are needed to form the joinery on anything wider — up to a maximum of 3-1⁄8" wide.
There’s nothing to take apart, switch around or shim for a proper fit. Chuck the bit in your table-mounted router, adjust the bit height carefully, and rout away.
Make yourself a pusher to support the parts on-edge and back up the cuts. It’ll also allow you to clamp the parts so they don’t get pulled in by the cutter.
The width of your stock is critical. Perhaps the easiest approach is to rip your pieces as close to 1-9⁄16” as you can. Then cut the joints, assemble them and hand-plane the top and bottom edges of the boxes to make all the edges flush.