The Lindberg 4CL is a good mouthpiece, but its sound did not impress me. It looks really great, and I had no problems with its narrow and rounded rim, which actually I like (some like it, others hate it). It resembles in size the Bach 5G, but with a shallower cup, narrower and rounder rim. It also resembles the Schilke 51C4, but the 4CL has a narrower and rounder rim, larger throat and backbore, and a more V-shaped cup. Of course, it is quite similar to the Lindberg 5CL too, the difference being mainly in the throat and backbore sizes (larger in the 4CL).
In terms of sound, the 4CL sounds very similar to the Lindberg 5CL, just a bit bigger in the low notes and heavier in the high notes. It requires more air than the 5CL. Compared to the Schilke 51C4, the Lindberg 4CL has a more brilliant and aggressive sound, and requires more air. Personally, I prefer the Schilke 51C4, because my experience is that the Lindberg mouthpieces sound great in solo, but they do not blend as well as the Bach and Schilke mouthpieces in a horn section. That is a matter of taste, of course.