I don't know the size for your specific quadcopter, but if you are talking about the dampening standoffs in the bottom right of that picture, there are similar items on various sites:

https://www.amazon.com/HONBAY-Vibration-Rubber-Fright-Controller/dp/B073LPTHCL/

You will want to measure the ones you have to determine the right size, but it's a common part.