All wallets on the Roolo site are multisignature and are implemented using the Block.io API. You can tell multisignature bitcoin addresses as they start with '3'. Roolo has implmented a shared multisig scheme under which each transaction must be signed by 3 of 5 keys. Two keys are held by us, two are given to you and one is deployed by Block.io. This means that if either Block.io or Roolo disappear, any coins you have in the wallet can still be accessed. Soon, Roolo will implement an optional private multisig scheme under which Roolo will not be able to move your coins and all your movements will be signed by you 'in-browser'.
Green addresses are bitcoin addresses created in Block.io wallets which are monitored by Block.io and from which it is impossible to double-spend. All payments are checked by Block.io before being signed and submitted to the network. Block.io will not forward any transaction which is a double spend to the bitcoin network. This assurance means that transactions from green addresses can be confirmed immediatly and coins can be transferred without waiting for even a single confirmation. It is this feature which allows Roolo to have all transfers 'on-the-blockchain' and instantly available to the buyer.
Roolo is cheaper to use than the main bitcoin trading sites. Roolo charges only 0.5% per transaction whilst other exchanges charge upto 1% to the buyer and the seller! The fee is subtracted from the coins delivered to the buyer - so if the buyer purchases 0.5 bitcoins, they will actually receive 0.4975 in their wallet. Thats it! Fast, secure and good value.