A type of barrier option for which the barrier strike is only active for a specific period during the option’s life. That means the barrier commences at a particular date after initiation and terminates at a particular date before expiration. If the underlying’s price breaches the barrier during the monitoring period (the window), then the option either knocks in or knocks out. Otherwise, it will end up an ordinary option and expire at maturity. Holders of window barrier options can reign in the effect of volatility during the “window”, and hence hedge their views on the range of volatility showed by movement in the underlying’s price within a specific period.