This app has a meditation timer you can set to any amount at 5 minute intervals. There are two “sound” choices, both decently pleasant. Also included is a mindfulness bell that can be set to intervals of up to 1 hour, or to play at specific times. Quite user friendly!
The free version of this app is fairly restricted. The time intervals are limited to 3, 11, or 33 minutes. This app offers a different layout for a meditation session, including a time interval for pranayama.