Genuine Dirt Devil Style 9 Belts Dirt Devil 3990220044 In Stock Ships Same Day Free Order Tracking Package of (2) Genuine Dirt Devil Style 9 belts, Dirt Devil part number 3990220044 . The Dirt Devil Style 9 belt fits Dirt Devil Vision Sensor models. I t is recommended that you change this belt every 3 to 6 months to ensure optimum preformance.