I recently purchased ICON clarinet barrels ( 64, 65,66 mm) and an ICON bell for my Buffet RC B flat and A clarinets that were manufactured in 1977. They were Buffet's top professional models at the time and in the opinion of many, its clarinets from that era remain competitive with many of the best instruments of today.
In my opinion, the combination of the ICON barrels and bell constitute a significant upgrade. While the appreciation of acoustic characteristics does vary from individual to individual, the ICON barrels and bell produced a darker, richer, more complex and more coherent sound throughout all registers. My instruments were easier to control and so there were improvements in articulation, response as well an improved capacity for musical expression.
The barrels and the bell individually produced improvements that were similar in nature but the combination definitely amounted to results that were greater than the sum of their parts.
Highly recommended as a relatively inexpensive upgrade that yields very impressive results.