Hoover Windtunnel Self Propelled Bagged Upright Vacuum OEM Genuine Replacement Part. Adjustment Knob P/N 38421094 Used in Good Condition. This Vacuum and Parts have been Discontinued,Parts are all Sold Separately and in Limited Supply. Compatible Models U6423,6425,6429,6430,7431,6432,6433,6434,6435,6436,6437,6439,6441,6445,6446,6449,6450,6451,6456,6459,6460,6462,6470,6471,6471,6476. If You Need It I Might Have It.