Just another scammer !
Don't wast your money !
I send an email to this company and ask for their address for see and testing befor buy but they say :

"We're not accepting visitors right now and there are no demo units available. You can purchase a small quantity through our website: https://halongmining.com/shop/dragonmint-16t-miner/

Please note, our MOQ is 5 units.

Richard Hogan
Halong Mining"

So there is nothing !
This is another lier same as another scammers !
They are cheater !
Don't waste your money !
I hate cheaters 
Regards