The Kana Tank is named as the best brush for woodstains & varnishes. Well worth checking these out if you have an upcoming project.
Best Exterior Woodstain to use on your home - Decorator's forum UK
The Best Paintbrush on the Market - Decorator's forum UK
Woodstain & Varnish Brush - 1.5in
Brushing Varnish Tips and Techniques for a flawless finish
brush Archives - Decorator's forum UK
How to Prepare Interior Wood for Stain
Axus Decor Wood Finishing & Varnish Brush (Lime Color) - 1.5/38mm
A brush for every type of painter – The Decorator
Minwax PolyShades Wood Stain + Polyurethane Finish – Quart, Olde
Bradite One Can Review - Decorator's forum UK
Interior & Exterior Wood Dye Stain Driftwood Collection