includes resistance to shock, centrifugal gravity, and vibration. In 2014, Casio introduced the GPS Hybrid Wave Ceptor feature in the GPW-1000 Gravitymaster that allows the watch to synchronize the time through GPS signals and also adjusts the time zone automatically. The MRG-G1000 is also equipped with this feature. At Baselworld 2015, Casio introduced the "Dream Project" (G-D5000-9JR) concept which was a Casio G-Shock square having most of its parts constructed of 18 Karat solid gold as part of the 35th anniversary celebrations of the G-Shock lineup. The watch featured premium finishes throughout its construction without compromising the basic shock resistance of a G-Shock. In 2019, Casio introduced the production version of the Dream Project which featured an upgraded module now incorporating Bluetooth time reception capabilities in addition to the radiowave time reception and began taking reservations at select G-Shock botiques in Japan. 35 units of the Dream Project square would be produced with each having a retail price of 7.7 million ¥ (69,500 US$ at 2019 exchange rates) excluding taxes making it the most expensive G-Shock watch to date. In 2016, Casio released the GWN-Q1000 Gulfmaster which was first G-Shock to incorporate quad sensors (pressure sensor, temperature sensor, depth sensor and direction sensor). It was also the first G-Shock to feature horizontal calibration which allowed the compass to be operated while the watch is being worn by the user on the wrist. In addition to that, Casio offered every function offered on G-Shock models till date. The GWN-Q1000 is the only analog G-Shock to feature a depth sensor as well as the first G-Shock to have carbon reinforced polymer construction for the case. In September 2018, to mark the 35th anniversary of G-Shock, Casio released a collection of four clear model of G-Shock watches called "The Glacier Gold" collection. In late 2018, Casio introduced the newest addition to the G-Shock Rangeman series of models. The GPR-B1000 is a GPS centred model, which can use the GPS receiver to maintain the exact time, down to the second. This model also has triple sensors (altimeter, barometer and compass) as well as a backtracking function which allows the user to return to the same point from where he started the journey by the use of a map, a function which was previously exclusive for Casio's ProTrek line of watches. The watch also features Bluetooth connectivity which allows it to connect to a smartphone