Purchased new and in excellent condition, only used for testing. The inner rim diameter feels similar to a Bach 1-1/4C to 1C, but with a flatter and wider rim that feels comfortable on the mouth. The cup is about the size of a Bach D, with a UV shape. The M cup, popular among Warburton users, not only makes high notes easier to play, but also has excellent low-note response and sound quality, making it suitable for pop, jazz, and horn sections. The 2M is efficient for its size and gives the impression of being easy to play. I think the high sound resolution and clear, unblurred tone are wonderful. The sound onset and evenness across the entire range are also noteworthy. Please give it a try.