Positioned on the reverse side of the watch sits the heavy duty solid stainless steel caseback, firmly screwed down into place to achieve a water-tight seal. Some companies use a push down 'snap into place' type of caseback which is cheaper but equally less secure for diving or water activities. The caseback is the access door to the engine of the watch, the internal integrity is of utmost importance, therefore we use a rubber sealant ring under the steel caseback (which is screwed down) to protect the heart of the timepiece. A special tool is used to apply enough pressure to turn and close the caseback so that an air tight lock is created, and the watch doesn't accidentally open during use. These watches are Swiss built, they are very durable and rugged; you can use it everyday in every setting, whether relaxing at the pool or exploring the Great Barrier Reef.