The Ruffwear Knot-a-Collar really is not a conventional collar at all, it's a little different. It is climbing inspired, pairing well with the Knot-a-leash which I love, and is predominantly constructed with a thin (7mm) rope core with reflective elements. This rope, available in four 'on-trend' colours, forms the collar and adjusts in size with two very clever fisherman's knots on each side. Slide those knots to fit your dogs head and then it is easily worn like a slip lead would be. Very easy on and off. I had great fun adjusting and then re-adjusting the knots, perhaps my time in the cubs, although quite some years ago, still resonates with me!
On that rope there are two metal mounts, the V ring at the rear where you connect the leash and at the front is what they refer to as a belay plate. In laymans terms this is the metal front side of the collar and it is where the rope threads to ensure none slip adjustment. Also on that plate is a connection to allow name tags to be mounted and a small circular silicon tag is already hanging from this. The reason for this tag is a simple one in that this reduces the jingle of a metal identity disc against the collar. A small but nice feature, these guys are always thinking.
When I first saw this I wasn't fan and I'm (very) often wooed by Ruffwear products. Despite my attempts to turn my dog into K9 version of Chris Bonnington the Knot-a-Collar didn't sing to me apart from the novelty factor. When using this on Denver I felt that the thin rope wasn't ideal for 'the one who likes to pull' putting too much pressure on a small surface area. In addition to this I found myself compensating my making the collar looser but that wasn't ideal as he managed to wriggle free a couple of times. That was my fault not the collar though.
With above said I did persist with this collar and it is still in use a week later so it obviously has some merits. So having formed an immediate 'not sure about it' view and outside of my own laziness to change it, I think there are a few reasons I am sticking with it for now. It is lightweight, is very easy to take on and off and it settles well into his thick fur. On that latter point Ruffwear state it helps prevent matting so the challenges I highlight on rope size offer an upside too.
In summary, the jury is out on this one for me, however I can see it's merits, especially for a dog who doesn't pull for fun like mine. When using it I find it great for when he is running free and I have to sporadically re-leash him when passing dogs or other shiny things. I haven't used it on the trails yet, however, I can see how this would work in this environment. So it's horses for courses on this one (or dogs for collars anyway), you could buy it and love it or it could grow on you, I'm in the latter camp but hey what do I know?
All opinions my own