I knew they exist when I bought a Boron 2 from Yonex. There was also a Boron 3 and a Boron 7, but exclusive to Japan. Last Friday, there were some 'older' players at our place. They had a very good technique, but there back were playing parts. So I discovered they played with some older rackets and when it got my attention, he showed a racket in his bag I never saw before. Not even on pictures! It was a Boron 7 from Yonex. He had 3 of them, but this was the only one left. Not in perfect condition, or I would made him an offer.
Certainly would love to have one if I can find one that is still in mint condition (is there an alternative to paying through the nose?).
I have ever read an article about this Yonex's Boron series. Among Boron 2, 3 & 7, Boron 3 & 7 are for JP market only, whereas Boron 7 is more solid and heavier among them. Boron 2 is the export version of Boron 3. It has been rumoured that the cosmetic and quality of Boron 2 & 3 are identical, but just change the word "3" to "2", making Boron 2 as an export version. , I have ever seen Boron 7 photos as attached, but never seen a Boron 3 before. It would be great if any one can show a Boron 3 here. Anyway, Boron series is a bit fragile, max. tension would be 22 lbs. A stronger alternative would be Cab 21, which is more solid and durable than the Boron series. I am so lucky to own a Boron 2 (95% new) and now I keep it as an antique. In terms of performance, Boron 2 is perfect ; in terms of cosmetic, I find Boron 2 is the best - simple design but elegant. One particular point here, the Boron series haven't had any YY logo on the T-joint, that's the unique feature of Boron series.
Didn't realise that YY Boron (racquets) are a bit fragile but thanks for the info so that I know now.