The pex 400 ae is the most powerful random orbital sander in the range it sits securely and comfortably in the hand due to its ergonomic design with softgrip coverings one of the key features of the pex 400 ae from bosch is its speed preselectionthis is an advantage especially when working on varnished surfaces if you select a low speed the surface will not get too hot and the paint on a workpiece will not burn