This Ryobi handle hinge cover is compatible with the Ryobi RY401014US 40V 21" walk-behind mower. It is made and is designed for self-propelled, battery-powered operation. The cover can be attached to the left or right side of the mower and is included in the items included with the mower. The voltage of the mower is 40V and it has a horse power of 2 HP. The cutting width of the mower is 21 inches and it has an electric engine type. Some assembly is required with the Ryobi handle hinge cover. These pop right in effortlessly.