A 35 mesh nylon bag that fits inside a 5 gal bucket. Drop a shovel full of gravel in the green bag and use the handles like a rocker sluice to work the fine gold out into the water in the bucket. Set the bag aside and check with a metal detector for flakes. No signal then discard and repeat. Very effective, inexpensive, lightweight and super strong. Good for holding smaller item like snuffer bottles, etc. I have never tried as a "dry" classifier so I do not know if it would work in the desert. Also works well for metal detecting finds and wet swim suits. The water drains and the dirt falls out. Paste the link below to view.
http://www.webcocustom.com/greenbag2.jpg
http://www.webcocustom.com/retailsales.html Scroll down to "Green Bags"