The Toro Lawnboy 106-4161 Handle Knob NOS is a set of 5 black handle knobs designed for gas-powered lawn mowers. Specifically, they are compatible with Toro, Lawn-Boy, and other lawn mower brands. The knobs have a diameter of 4 inches and are ideal for replacing worn or damaged handle knobs on lawn mowers. The model number 106-4161 indicates the specific design and compatibility with the Toro Lawnboy series, making it a reliable and high-quality choice for maintaining and repairing your lawn mower.