A rotary lawn mower includes an internal combustion engine having a power take-off. The mower further includes a connector adaptor attached to the power take-off, and a lawn mower blade. A connector base of the mower is attached to the blade. The connector base and the connector adaptor have extensions designed to interlock the connector base with the connector adaptor. At least one of the extensions forms a J-shaped structure arranged longitudinally along an axis of rotation of the connector base and connector adaptor.