I got these laces for a pair of Chippewa boots that had previously had some cheap nylon core laces on them.  These laces are well made -- the jacket is well woven and, with the black and brown color scheme, they look good on my black and brown boots.  I have no worries about them staying tied; they have a small bit of stretch in them when they're pulled tight, but they spring back when you stop pulling them.  They're substantial laces -- I wouldn't try to use them on shoes or light boots.  They seem incredibly durable.

The only caveat I have, and this has nothing to do with the quality of the laces, is that you should watch the price here.  The card that holds the laces states what the price should be, and Amazon.com is currently charging almost double that.  I usually get good deals here, but I felt a bit like a chump for overpaying on this one.