Universal Timers is a flexible interval timer app designed for sports training, including specialized support for activities like apnea or climbing training. Create custom timer bundles with multiple blocks, each containing work and rest phases that can be repeated.

Key features:
- Create custom timer bundles with named blocks
- Configure work and rest durations independently
- Set repetitions for entire blocks
- Dynamic duration adjustment: Use delta fields to gradually increase or decrease work and rest times during a set
- Minimum duration limits to prevent values from going negative
- Clean, modern Material Design 3 interface
- Dark mode support
- Swipe to delete timer bundles
- Save and manage multiple timer configurations

The delta feature is particularly useful for progressive training; for instance in apnea training you might focus on improving CO2 tolerance or O2 deprivation which some designated apps train by decreasing breathe-up times or increasing breath-hold times, respectively.