I purchased this Profile Spider to replace the original spider fitted to a GT pro series that was damaged over time, because of an incorrect rebuild. After contemplating if I should get a sprocket or just keep the original chainring and replace the spider, I chose the spider as I realised this is made for a 19mm axel and the previous I had used an adapter reducing the spiders center hole to 19mm. As this was incorrectly fitted previously and caused the old spider to slip and ware unevenly, this new spider should never have that problem as it is 19mm so I am extremely happy with the fitment and it just feels a very strong robust part. Lightweight and a worthy replacement of the original part.