Considering the refurbished Antminer Z15 420k for coin mining? It's a tricky question. While these offer the potentially cheaper entry point into ZEC mining arena, one must assess the factors carefully. Used Antminers, https://budget-z15-miner621996.blogginggrowth.com/70762/a-refurbished-miner-z15-420-000-is-it-sound-digital-choice