Just a small thing, CPM M4 is not a true stainless steel, seeing as it only has around 4.5% of chromium, whereas the "accepted" minimum amount required to be classified as stainless is ~12%. That means it will need a bit more care to keep it rust free; cleaning it after use, keeping a coat of TuffCloth or mineral oil on it if it will be stored, etc. Otherwise, a tough tool steel that holds an edge for a long time.
JakeRobertsGenerally, unless in a very humid environment it won't rust, but it will likely patina. M4 is a good steel but it's a mystery why they used it on a good looking gentlemen's folder.
JakeRobertsActually, M4 is not a stainless steel at all. It's a tool steel with not even close to enough Chromium to classify as stainless (11% is the minimum.
If dried after use though it'll probably never rust. Merely discoulor. But that has not adverse consequences.
JakeRobertsA lemon juice patina is extremely easy to apply to this blade. This knife is a top notch pocket knife for the office. Perfect size. Unbelievably light weight when you first pick it up.