Semi-permanent eyelash extensions are individual lash-like fibers attached millimeters above your eyelashes, where you'd usually apply eyeliner. As your eyelash grows from 30 - 90 days, the extensions will fall out with your natural lash and replaced by new younger lashes. Single lashes take about 1 - 1.5 hours to apply. The extensions typically last three weeks to three months, but can fall out within days. You can even shower or go swimming in them .To maintain the full look, refills are required between 2-4 weeks.