Peer-to-peer payments have arrived on wearable devices with the arrival today of Square Cash for the Apple Watch.

The service, with offers a simple numerical keyboard on smartphones, employs a dollar-bill layout on the watch, as seen here. Users tap bills until the correct amount is reached, similar to CIBC’s funds transfer app introduced last May. This is an interesting solution, as a keyboard would likely fit on the screen, but the bill-based entry may be easier for tapping fingers.

The app also allows exchanging funds with nearby devices using Bluetooth. Funds can be accepted with a simple tap.

Square continues to build delightful apps for consumers, while its true customer base remains merchants. There is a Square Cash for Business, which allows merchants to request payments via Apple Watch for a 1.9% fee.

Jack Dorsey, Square’s co-founder and CEO, remains at the helm at Square, despite also taking over as interim CEO role at Twitter, which he co-founded. Square was launched in 2009 and now processes over $30 billion annually.