Rear wheel cylinder question

Does any one know what size star socket is needed to remove the real wheel cylinder on a 98 2.4 5 spd. sunfire convertible?

If you can find one of these they work pretty slick. They are made by Lisle tools
http://www.etoolcart.com/ProductImages/brake/LIS22070-L.jpg

Otherwise I think its an E8 torx