To me, being a painter myself,  it was only logical to use nothing but the very best in CLING ON! brushes…
So about 75% of it’s filaments are Tynex® nylon, supported by 25% of Orel® polyester in shorter lengths to add some stiffness.
Apart from that, although some still claim that it’s perfectly normal for even a  more expensive brush to lose bristles in the beginning (!!), the filaments are completely locked in epoxy resin to prevent loss of hair, as is the handle, making the brush a whole altogether.
No risk of loose bristles, ferrule nor handle.
What about cleaning??
As said, cleaning nylon filaments is quite easy. No gallons of increasingly precious water needed.
Some will tell you to clean your brush and let it dry….
However, there will always remain a tiny bit of paint remnant in the “heel” of the brushhead, near the ferrule. Should you store the brush dry, after cleaning, there is a risk of drying in of the paint remnant. This causes the heel to harden and this gradual build-up will affect the shape of your brush, actually shorten the effective length of the filaments and diminish it’s ability to pick up (and release) the paint.
It affects your painting result!!!