The B3WN series achieves excellent seal-ability by switch itself, passing various seal-ability tests as shown here.  Not only the standard watertight test such as IEC 60529 degrees of protection provided enclosures (IP code), but the switch also passed a detergent resistance test, a humidity resistance test and a gas resistance test.  The unique advantage of Omron’s B3WN series switch is that these kinds of seal ability are achieved only by the switch itself, without sealing by final application.