those little things that hold a wheel on an axle. I have my wifes vacuum cleaner tore apart, and the wheels were held on with the little round things made out of spring steel that just drive on with a mallet. It is not a snap ring that is open on one side, but a complete cirle that sort of bites into the axle. It is almost impossible to get them off without breaking them, and now I need two new ones. But, I have no idea what to ask for.