Page 65 - Mario Bigon "The Morrow Guide to Knots"

CONSTRICTOR
KNOT

This is a simple and secure
binding knot, but if it is pulled
too tight it is hard to untie.

Method
Take two turns with the rope,
making an overhand knot in
the second (1,2,3). Thread
the leh end under the first turn
and tighten (4,5).

4
2 5