CodyScottCochrane wrote a review of Ruffwear Knot-A-Collar Dog Collar on February 9, 2014
Familiarity: I've put it through the wringer
Looks good. Works well. Metal eyelet on the back makes Leashing a breeze. I haven't had the slipping issues as mentioned in other reviews.(I have a 55 lb Black Lab Whippet Mix, who pulls constantly on leash[Working on it}) The knots are made to slip so its easy to use but the 180 turn they do through the front metal piece creates quite a bit of tension between the inner bends of the rope and the eyelets. Making it pretty hard get those knots to move just by pulling on collar.
A tip for less slip: After Sizing your dog to snug but comfortable size use both of your thumbs to push the loops of rope onto the face of the front piece. Then a slight adjustment of the knot postions to compensate for any slack created by this. The key to no slipping is the slight tension from the knot to metal eyelets.
As for Noise, their rubber tag does help but doesn't solve the problem of the tag hitting the metal front piece to which to mount. 2 possible solutions for future models for Ruffwear: Rubberize the front piece, increasing the grip on the ropes and reducing noise from tags. or put a rubberized logo on the piece, this deaden the initial sound and dampen any ringing.
Easy Homemade Solution: electrical tape, heat wrap, Vinyl Stickers or good ol duct tape. If done right this doesn't have to look trashy, will not make it silent but take the metallic clamor out of the jingling.
Advanced DIY Master Solution: remove rope from collar to free the front metal piece. Scuff with steel wool, prime and then use Spray - on Rubberized undercoating or bed liner. I would mask the eyelets for the rope, as the ropes movement will likely wear the rubber quickly anyway.
Is there room for improvment? Yes.
That said, this is still one of the better designs for a Dog collar I've found to date.