This lace is a nylon core with a woven sheath.  It's a little fatter than some, but still fits in the speedlace feature on my boots.

Some reviews mention the "off" color.  Not sure what they're referencing, as the laces I received are brown as advertised.  Besides, boot laces aren't a fashion statment in my world.

Four stars instead of five due to girth, not function.