What is the fine-grained topic of the following text: Ripple’s most popular product, xCurrent, helps banks to settle international transactions by using blockchain to confirm transactions in real-time at each stage of a cross-border payment and last year the company teased xRapid, a similar system that uses the XRP tradable token directly. Only return the topic.
Ripple's blockchain-based international transaction products (xCurrent and xRapid)