3” wide, for applying varnish and paint. Buy a case of 40 and save $10! 

These are the brushes we use for applying and "tipping out" varnish and paint on the CLC showroom boats.  These don't melt the way the cheap home center foam brushes do, although it may still take two brushes for an entire coat of varnish on a kayak.

Read this shop tip for ideas on how to get professional finishes.