I used these on my M05 pro. the bearings fit perfectly. I did not need any extra bearings. I just swapped out the plastic ones and bolted these right on. If you have a M05 pro they work great. Plus the added bling factor.
If you wish to simply swap your current plastic arms over do not just purchase these arms you will require smaller bearings plus a set of these http://www.rcmart.com/catalog/product_info.php?cPath=595_744- _707&products_id=22333
oh and you will need the correct bolts as well.
The product is excellent the descripiton doesnt state this and it is a 3Racing not an error of Dinball.