If you are looking for a great deal on a sling pack, then this is the one for you. As this pack (retails for $29) regularly goes on sale a few times each year, it can be purchased for as low as $19.99 - right now it's $20.99 on the Cabela's web site.
The Cabela's Advanced Anglers Sling Pack has a couple of little slots on the pack for which you can loop a net cord through and perhaps some carabiners. The sling pack is light and dries out quickly. There is space enough for a few small to medium size fly boxes and perhaps a bottle of water (or attach water bottle on exterior) and snack. It's got a band that keeps the pack from sliding around when you bend over. When sliding the pack around for access into the pouch or pocket, unclasp the band and pull the bag up or down. I'm somewhat a gear minimalist and prefer to keep wading light. If you are looking to save a few bucks and have a proper sling pack, this one is for you.
I can loop my camera through a strap and the fly box is attached to a zipper on a carabiner. The net was looped through a slot hole in the back.
Room enough for a few medium size fly boxes and a Martin fly reel.
Cabela's Advance Anglers Sling Pack http://www.cabelas.com/product/Cabelas-Advanced-Anglers-Sling-Pack/1571765.uts