ABOK #1188
This knot is like a Clove Hitch tied over an overhand knot.
This is the acme of compact binding knots, an alternate to the Strangle Knot, with such a tenacious grip that the ends can be trimmed close to the knot without it coming apart.
The Constrictor is generally regarded as a semi-permanent seizing that must be cut off when no longer required. Budworth
If the diameter of whatever is being bound is large, double the diagonal part to make the Double Constrictor.
The constrictor knot is one of the most effective binding knots. Simple and secure, it is a harsh knot that can be difficult or impossible to untie once tightened. It is made similarly to a clove hitch but with one end passed under the other, forming an overhand knot under a riding turn. Wikipedia