These Rails work with Mountain Adenalin accesoiries but are made out of aircraft grade aluminum instead of plastic. Rails are also designed to bolt right onto Matrix chasis Polaris snowmobiles using there factory T slots in the tunnel which means NO DRILLING for you Polaris sled owners. The other holes line up with the original solid bar mountain adenalin rails so if you already have the plastic rails you can upgrade to these with out drilling more holes into your snowmobile tunnel.