Commonly known as spring steel, 5160 has excellent shock absorbing properties making it resilient to shattering and extremely durable as a knife steel. We harden to 57-58 Rc to maximize its performance.
I carry the Buck folding saw in my mountain bike pack everywhere I go. I've probably removed 30+ downed trees from trails over the past 15 years with it. It's never been sharpened and still cuts like a hot knife through butter through any tree 6" or less in diameter. Folds up to protect itself and your pack when not in use. Light enough to live in my pack all year.
When thinking about buying this, please consider the price point. I bought this saw expecting a light, plastic-handled saw with a sharp blade and okay/good ergonomics. It delivers all that and more. The lock is sturdy and produces a nice snap. The blade was very sharp out of the box and it rips through branches. I bought it along with another super-popular folding saw (made in Sweden) and this Buck model beats it at everything (including price!). Finally, I love that Buck actually reports what type of steel the blade is made out of (other brands do not do this for their lower priced saws).