This is for an AR15. I haven't utilized it yet, but it does match the size of my ar15 rings. They make another one for the AR10, it has a .308 attached to the name. I'm not sure whether I am going to install this yet. I am keeping it as a backup as of now. The difference between 3 and a single helical is that the 3 rings have a little play in them to allow for tolerance differences on the bolt inside the bolt carrier so that the gas is trapped where it needs to be. Basically, this ring will have to match "perfectly" with the bolt and carrier to work correctly, otherwise it could be too small (for the carrier) or too large (for bolt) depending on where the bcg came from. If it does work with your bcg, then it would be an excellent upgrade, but that is a gamble, although its only a gamble of about $4. Hopefully I have thoroughly answered your question.