Very fragile tip, use with care, and as per leaflet, DO NOT apply pressure, tip will break Human use only. Avoca Silver Nitrate Caustic Pencils are designed for multiple use for a single patient. An Avoca Pencil contains approximately 350mg of silver nitrate & potassium nitrate mixture. Used for removing granulation tissue, warts, for cautery and as a caustic. This red carton and red plastic holder signals a 40% silver nitrate mixture. From the date of manufacture, all Avoca Pencils have a 5-year shelf life.Max 3 days treatment. Full details: https://www.avocamedical.com/usage/how-to-use/The details on this website are a summary only, for full details please refer to the manufactures for full product details.