This extension allows you to time-box your work
Time Box is a simple app that allows you to have a better handle on your time management.
Using this chrome extension, you will be able to set certain time limit (time box) for any given activity, you will get an alarm at the end of that time period. After the alarm, you will be given a break time, once the break is over the time box will restart automatically.
You will have the option to set the time-box limit and the break time limit.