To fit Flymo double auto feed twin line grass trimmers. Suitable for: Double autofeed (twin line) models. Contour, Contour 500, Contour 500 Power Plus, Contour 700, Contour 700 Power Plus, ET23, Minitrim Auto 2003, Minitrim Auto Plus, Multi Trim 250D/250DX/300D/300DX, Power Trim, Power Trim 500 (product no: 9648596-25), Power Trim 700, Revolution 2000/2300/2500 (twin line), Twist'n'Edge. Compares to 5137651-90/6, 5137651-01/3, 5139371-84/9, FLY021.