*PLUMBERSSTOCK EXPERT* responded:
Hello! If you're asking about the outside diameter of this Moen AT2199AN replacement shower arm flange, then, no, it is 2-1/2". We haven't been able to get the information about its inside diameter but this Parts Breakdown Sheet shows that it works for the following trim series: T2801, T2802, T2803, and T2808. If you have a different model, please give us its specific product number so we can help you find the appropriate replacement flange for it. Thank you for visiting PlumbersStock.com!