I do have the upgraded aluminum Redcat shocks and I am very happy with them. I have shopped the crap out of them for the best price and in my experience you can't beat this website for all Redcat upgrades www.redcatracing.toys.com . Check it out. You won't be sorry. So here is the skinny on my hub extenders that work best. I bet yours are GPM if they are from China and they are 25 mm.That is a good thing because I have found they work out very good with some slight modification. Assuming yours are GPM you will need to do the following. The end that goes in to your axle is too small so you will need to drill them out to 1/4", I'm sure in actuality it is the metric equivalent of 1/4" if you have metric drill bits. If not 1/4" will work just fine. I would recommend starting with a smaller size and working your way up to 1/4". You need to be careful because as you will notice when you get up to a 1/4"size hole you are running out of the thicker part of the aluminum on the hub extenders and I think it is important to keep this as thick as possible, especially if you are running 3s. Look at your axle and measure the thicker part (beyond the threads the part that has the hole for the pin) and this is how deep you need to drill your 1/4" hole. Just play with it and take your time. An additional step I took which I got the idea from another set of wideners I had and I highly recommend is to get some 3 mm set screws (which are hard to find) and get yourself a 3 mm tap if you don't already have one. Put at least 2 set screws in the hex wideners to help secure them on the axle. I just don't trust the little pins alone holding the wheel and the wideners on the axle. Also mine were a bit loose until I did this step. I hope this helps.If you would like some photos of this please send me your cell phone number and I will get them to you. Good luck. Jeremy