Kong Signature Rope Dual Knot 20" Tug. Kong Signature Dual Knot Rope has a unique braid of cotton and fleece that provides an uncompromised stretchy delight that is gentler on a dog’s mouth. The durable material ensures that natural chewing behavior is rewarded again and again with the added benefit of helping clean teeth. The two knots double the fun while making games of instinctual tugging even more engaging.