Mortein Odourless Refill is the easy way to provide night-long protection against mosquitoes and flies whilst you sleep. This one refill provides up to 30 nights of undisrupted sleep, with no need of changing the refill on a daily basis. How to Use Remove the plastic cap of the liquid refill bottle. Screw the liquid refill bottle onto the heater by rotating in a clockwise direction. Pluf the cordless gadget (220 V) directly into a socket. Only use gadget in an upright position. Where to Use For indoor use only. Use only in the vertical position