Squeak-Ender, also known as the Squeakender squeaky subfloor repair kit, has an unusual but effective design. Its main purpose is to pull the subfloor securely to the joist.
Squeak-Ender has two main parts: The first includes the hanger bolt which fastens to the underside of the subfloor against the joist with four provided screws. The second is a bracket that slips over the joist and the hanger bolt. Finally, install the washer and nut and tighten with a wrench until the squeaking stops. Be careful not to overtighten.
After testing the product, I have a couple of recommendations. You may want to consider a lock washer. Also, if you plan to finish the ceiling, notch the bottom of the joist to recess the joist bracket. This will help maintain a smooth surface for the later application of wallboard.