You must tighten gently with the tool provided as over tightening may deflate the tire. O-rings in valves don't stay in; So if you want to air the tires, be careful with the o-rings.
Pros
βοΈ SUPERIOR MANUFACTURE: This tire valve stem cap is made of zinc alloy, integrated design and surface plating to prevent metal oxidation, rust, and improve corrosion resistance, wear resistance, texture and gloss.