Dog Knot is a high quality penis sheath made from soft and pliable silicone.  It measures in at 6 inches in length and width of 2.1 inches at it's widest point.  The internal diameter is 1 inch, whilst the silicone is super stretchy meaning it'll accommodate any size of penis while hugging it comfortably.  If your anatomy is long enough, it might even protrude out the open end of this dirty little dog.