Guys,I want to make acouple of mobile bases for my PM30 sander and Giz drum sander.I can fine ever kind of caster there is on earth but,I cannot fine the ones that you roll around,swivel,then you flip the lever with your foot and it lowers to the floor.You have seen them on just about all the store bought mobile bases.I think they are called foot control casters.What is the proper name for them and where on earth can a person perchase them.Thanks--SMCer's Carroll