pack
shelter
sleeping bag
sleeping pad
The big four is a shorthand way of referring to the heaviest and most critical pieces of gear you'd be carrying on a backcountry trip. Making sure to have high quality and light gear for these items are a significant hurdle to lowering overall pack weight. This tool gives you a bunch of the best price/oz gear for you to choose from and tallies the cost and the weight accrued. No matter how hard you try the gear here can not be combined in a way that exceeds 5.5lbs(2.5kg).