This extension displays the ISO week number and calendar UI. The extension shows the current week number in the extension badge also - that means easy to find out current week number. In the UI, the current month is displayed with the week number for each week. UI provides option to move to the previous and next months to find past and future week numbers. UI also provides an option to move to previous and next year. UI allows to pick a year from the drop down list. Simple to use, great usability.