2.The guarantee only applies to the original purchaser who obtained the equipment directly from BITMAIN. After the miner is resold, guarantee protection becomes the accountability with the re-vendor. Guarantee When the miner is employed at an altitude from 900m to 2000m, the best working temperature decreases by 1℃ For https://batchminer.com/product/bitmain-antminer-s19j-pro-100th-bitcoin-miner/