The first number, '6', in 'IP 68 rating' is completely dust proof, and shows the device has complete protection against any dust contact. The second number '8' is protection from immersion beyond 1m. The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. Normally, this will mean that the equipment is hermetically sealed. However, with certain types of equipment, it can mean that water can enter but only in such a manner that it produces no harmful effects.