This replacement part for your Dyson DC24 cures the common fault that is the ball clunking and becoming loose when the machine is being used. You must unscrew the ball to fit this little cog. One side has a large cog (that seldom wears), the other (that does wear) is this smaller one. There is a fitting tutorial on Dyson Medic in case of need. This fits ALL Dyson DC24 models and variants, but not any other models. So please do not buy it for another model or if you are unsure that your machine is a DC24. The video we produced to show you how to do it can be found on Youtube by searching 3OVx3IzntsA on there. Please note: This part is a non-genuine compatible spare part and any manufacturers names and/or part numbers are used for reference purposes only.