Sono - S1 S2 Speaker Control is a multimedia application developed by Fiision Studio Company Limited for iPhone users. The app is a third-party product and not an official product of Sonos, Inc. It is designed to cast and control Sonos Speakers from your iPhone with ease.

The app automatically detects nearby Sonos Speakers within your Wi-Fi network, and you can easily switch between them if you own multiple speakers. You can stream music from both the internet and local storage, and the app will automatically resume your previous cast session.

Sono - S1 S2 Speaker Control offers a full version license with three subscription plans: Lifetime for $14.99, Weekly for $1.99 with auto-renew, and Monthly for $4.99 with auto-renew. Subscribed users can access all premium features without ads, while non-subscribed users can only use the premium features a few times a day.

The app is compatible with most Sonos Speakers and offers a simple connection process. However, the subscription model may be a drawback for some users. Overall, Sono - S1 S2 Speaker Control is an excellent third-party app that provides a simple and efficient way to cast and control Sonos Speakers from your iPhone.