Shepherd Hardware Slideglide 1 1/2" Furniture Sliders 9455
The Shepherd Low Friction Base Slide Glides measure 1-1/2 inches in diameter.  They are screw-on and designed for use on all non-abrasive floor surfaces (low pile carpet, vinyl, hardwood, etc.) and allow furniture to move smoothly over floors.  They're for use on heavy appliances and furniture such as couches, desks, beds, etc.  They come four per package.