Shimadzu Corporation has begun selling the world’s most accurate clock, the strontium optical lattice clock, for 500 million yen ($4.5 million).

Axar.az reports that this clock is accurate to a deviation of just one second over 10 billion years, making it 100 times more precise than traditional cesium atomic clocks.

Developed in collaboration with the University of Tokyo and Riken, the clock will be used for advanced scientific research.

The company plans to sell 10 units over three years, both in Japan and internationally. Though this clock is the most accurate available for purchase, more precise clocks are still under research.