Mining rig rates corrected sharply over the board when BTC value dropped mid-year, but have due to the fact rebounded. D-Central Technologies stands with the forefront with the Bitcoin mining industry, not just as a service provider of mining options but as being a pioneer in the refurbishment of Antminers. https://buyrebishedantminerz15.wordpress.com/where-to-buy-refurbished-antminer-z15-online/