Microsoft launch another updation of window 8.1 for  Preview for Developers user know that first update of 8.1 have launched in mid of May and it change the full user view. This new update is a Third update launch by Microsoft.

The second update come after 10 days ago after first update now third available with some fix bugs but you not see any change in function or view and this update is low in size and user easily install in few minutes.

How to install go to Settings > Phone Update > Check for updates.