Hypoallergenic Crystal Glue is waterproof and thoroughly tested to ensure the highest quality and safety standards available for eyelash extensions. It is the premium glue with the extra care formula to minimize the potential for allergy and irritation. This eyelash extension glue should be used by trained professionals only and recommended for use especially for those with sensitive eyes, allergies or contact lens wearers. It provides a 2 second bond performance and holds for 2-3 weeks before refilling is necessary. The glue complies with all Health Canada regulations. Ideal humidity levels are 45% to 65% for optimal results.