SparkFun COM-10594 Silicone Bumpers – Large (10×16.5mm, 4 pack)
Rubber feet raise your PCB or project up off your desk. This helps prevent short circuiting from bits of scrap wire floating about or setting a project down on a conductive surface. They also prevent your enclosure or PCB from sliding around. They can also be used as feet for enclosures. These are self-adhesive and 16.5mm in diameter and about 10mm tall. They taper to roughly 12mm at the top. They come in a set of 4.