I bought an old (1910 ish) R&C tenor a couple of years ago that had not been played since the mid 70s.
In the case were several old tenor mouthpieces, a Lewin with side rail lig, the inevitable short shank C* Selmer and a Colletto.
The Colletto was a revelation. Small, about the size of an Otto Link, it is hard rubber with a bronze shank. The chamber is quite small with a slight roll over baffle at the tip leading to a drop off rather like a No. 2 Berg.
The performance is quite astounding. Once familiarised to the small tip it does pretty well everything. The altissimo, down to low Bb are ridiculously easy; also it can generate a dirty/gritty/ buzzy sound better (worse! ) than any piece that I have ever tried.
Any failing is that the bottom end is not as “phat” as my RPC and sub toning is not easy, possibly due to the smallish chamber.
It seems that this piece was made in Italy (forni) by one Professor Colletto, probably in the 1960s or 70s but I have been able to find nothing about this manufacturer…no-one on SOTW knows anything of the Colletto mouthpiece; perhaps the discerning & knowledgeable contributors to this site know something.
I have bought another Colletto from eBay Italia; a sleek metal No 8* with side rail lig, but it does not compare with my ugly little HR/bronze job. How I wish I could find the same with a larger tip opening…perhaps however, it would not be so expressive.