The skin markers are perfect for skin marking event and heat numbers at swim meets. They are also great for identification, self expression, or inspiration at water sports events, fun runs, and charity walks/runs. The two marker pack comes with in a re-sealable plastic storage bag. Unlike most permanent markers, SportSafe marker inks are made with tox-free cosmetic ingredients, are water proof and sweat proof, and can last several days unless removed. The ink is removed with most hand sanitizers or by rubbing area thoroughly with a damp rag.