I have a Lab/McNab cross who is a heavy chewer and needs a lot of stimulation to keep from getting bored.  Nylabone is an excellent product and this toy in particular keeps her occupied for hours because she loves the shapes and edges to chew on as well as the little nubs.  I know she wants to gnaw them off and works on it long and hard but the material is very durable and while she eventually is able to scrape a little off it takes a long time.  She isn't able to get chunks off that could cause problems if she swallowed them.  Highly recommended.