A perfect tool to remove the stuck on wiper arm that has'nt been off for years. Pulls the wiper arm squarley off every single time. The sprung load arm ensure a pefect pull everytime. It can also be used for removing over tight battery terminals and some alternator bearings. Jaw opening 6-28mm for wiper arms with an o/d up to 42mm. This item is top quality, designed for professional use.