Two low profile brass tubeless tire valve stems. These are commonly used on tubeless farm implement wheels to prevent stem knock offs due to a stem that sticks way out. They mount flush in the wheel and only about 9/16" of the threaded valve stem cap protrudes on the outside of the wheel. They are supplied with grommets for both the smaller .453" and larger .625" valve stem hole so they can be used on wheels with either smaller or larger stem holes. The nuts go on the inside of the wheel. You snug it in the wheel with first nut and then hold the first nut while tightening the second nut against the first to act as a jamb nut to lock the first nut in place. DO NOT over-tighten these or you will cut the grommet especially on the larger .625" stem holes.