Reopen, just to give some information and correct errors, also and above all on the Wiki.
Let’s start with the story of the machinist’s error for the creation of the return system (the S.i.d.r.o.m.s.) … pure fantasy, there was never any error, it was thought to be like this from the beginning, more (2nd error in the Wiki) Niubi has nothing to do with the Roo-yo brand, he was one of the three founders of the Brokenyoyos brand (together with Saxa and Speed12), the Roo-yo brand was owned by Stefano Benassi (Steeeve) and di Taso, here you find the story, if you are interested in deepening (it is in Italian).
http://www.yoyomaniacs.it/2009/12/produttori-italiani-roo-yo/
The return system is functional but it is not the best (in fact subsequently this system has not been used by anyone), the o-rings can be positioned more or less in depth but the string in the winding phase will always tend to push them to the bottom, therefore the possibility of response regulation is almost a marketing statement.
In addition to this, the response and return are never constant, sometimes they are ready, others tend to delay or not cling preventing the yoyo from returning … it all depends on where the loop is located at the precise moment of the bind, if in correspondence to the o-ring or in the gaps between them.
This characteristic, which is not exactly positive, is also found in the return system of the “R” series of the Roll-Out (SRS - Sight Response System) which, although of different workmanship, was inspired by the idea of S.i.d.r.o.m.s.
modifications with recesses dug to accommodate fluid silicone are not rare in order to remedy these problems.
(Roo-yo Kaizen)