Really nice mouthpiece, wanted to try as I love the Wick 4fl I usually play but to my ear it can sound a bit tubby. The 4Bfl is a bit lighter/brighter in sound and less deep. It's exactly the same depth as a Wick heritage 4 cornet mouthpiece (measured), slightly deeper than a standard Wick 4 cornet and a lot less deep than the Wick 4fl. Really like the tone and makes switching from Wick cornet to flugel mouthpieces very easy. Less exhausting than a Wick4fl which is good!