THIS is a recommended extension? Really?

Go download "eyeCare - Protect your vision" extension instead.

You can use a slider to set the time you want, and it flashes the icon when done, along with playing the sound of your choice, telling you when to take a break. You can use it for taking a break as well.

This "Tomato" clock is easily surpassed by free apps you can download on Github.

Only has a tomato option for 25 minutes which is too short. Not sure why it's not customizable.