Feliway Classic 30 Day Refill is a 48 mL vial containing a synthetic copy of the F3 feline facial pheromone, designed to be screwed into a Feliway Classic plug-in diffuser unit sold separately. The diffuser should remain plugged in continuously, with the vents pointed upward and at least four feet of clearance above it, so the vapor can disperse throughout the room. One vial is formulated to cover an area up to roughly 700 square feet and is intended to be replaced about every 30 days for continued effect. The refill is meant for indoor home use in spaces where cats spend the most time, such as during moves, new pet introductions, or other routine changes. The diffuser head itself should be replaced approximately every six months. The vial contains petroleum distillates and should be kept out of reach of children and away from open flame or heat sources during operation.