Thanks for the info.The only references I found to G5 fibres was here
Style & Swagger
www.thewetshavingco.com
But now they have changed the ad to G4 so it looks like I was misinformed.
Nevertheless I like the brush and knot very much Alin.
Edit: they have Oumo G5 knots available
It seems I guessed right: Bali, Everest, Atlantis and Robin have the same knot (G4 fiber). I had some G4 brushes and I didn't know!
Yaqi China does not give this information about synthetic fibers used in brushes!