fia0001 's Japan Review

For those who use fit shafts, which tend to loosen easily, but other o-rings stick out! I would definitely recommend it to those who use fit shafts and tend to loosen easily, but other o-rings stick out!

I use "Monster's barrel" and "fit's slim No. 8", but they are not compatible with each other or something. And when it is loose, the threaded part may be under extra strain, or it may break off frequently. I tried to use a foreign-made o-ring for a while, but the diameter was too thick and it protruded from between the barrel and the shaft, creating an unnecessary gap between the barrel and the shaft.

This product solved that problem.
As expected of Cosmo, the company behind the fit. It doesn't stick out and doesn't loosen even though it is thin. Thanks to this product, the shaft has not broken so far. If I keep using it, I'm sure it will eventually fall off badly and break, but that's just bad luck, lol.

One drawback is the price.
While other foreign-made o-rings and even domestic o-rings cost about 200~300 yen for about 20 pieces, this one costs 400 yen for 12 pieces. It is quite expensive. If the stress of shaft loosening is relieved and the shaft lasts longer, I think the original cost is enough.

For this reason, we deducted one star for cost performance and gave it 4 stars.

O-ring arrived today. Installation was surprisingly easy. I threw it immediately, and it does not loosen between the barrel and the shaft at all even though I threw it quite a bit. I feel like a fool because of the stress caused by the loosening.... I wish I had bought this product earlier.
The o-ring almost came out when I tightened it, but if I put the o-ring to the end of the thread (open one thread), I was able to install it beautifully without the o-ring coming out (I am using a special shaft for fit flight).

I recommend this to anyone who is frustrated when slowing down due to a loose shaft.
This will relieve your stress!!!

If you have a barrel and shaft that don't match and tend to be loose... I recommend this.
It eliminates the stress of having to close it every time.

The shaft hardly loosens at all.
I no longer have to stress about re-tightening the shaft every time I throw.
I would like to repeat this when I run out.

It prevents the shaft from loosening, thus reducing stress.