Rainflys: Hennessy Hammock Catalogue. Hennessy Hammock. EXPEDITION HAMMOCK - www.mosquitohammock.com. We use a double layer system on the bottom of the hammock with Nylon on the outside and Polyester on the inside. The Polyester feels softer against the skin, and the two layers slide across each other so you can move around and sleep comfortably. The double bottom layers also make it harder for the mosquitoes to bite through. The heavy duty YKK double zips open from the inside and the outside and run the entire length of the hammock. They make it very easy to get in and out of the hammock, and they will last a long time. Clark Jungle Hammock.