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You will get far better returns on your money by investing it in steem and powering up. I have Genesis contracts and you as the buyer carry all the risk for very low returns

And you are gambling on the ROI as well.

be more precise:
codes are used to get 3% discount - the extra (equal to 2.5% of the contract price) hashpower goes to the referrer
PS
talking about BTC contracts - better wait till 11/07 to see the cloud mining rewards after BTC halving