Built for the ocean adventurer, the Reactor Heavy Water watch model 71801 features a unique rail system that allows airflow under the watch to prevent skin irritation during those times you are constantly in and out of the water. The Reactor Heavy Water also features an extra thick hard mineral crystal which maximizes scratch and shatter resistance. Each Reactor Heavy Water watch is individually depth tested to 200 meters and employs Reactors triple O-ring screw down crown system. Model 71801 has a unidirectional countdown bezel, black coral dial and quartz movement with date display. eWatches.com is an Authorized Reactor Watch Dealer.