The ESEE-4 is one of the most popular ESEE knives ever made. With its 0.1875" blade thickness, it's the perfect blend between toughness and cutting efficiency all in a small package. If you can only choose one, then the ESEE-4 is the do-all workhorse of the ESEE line. These knives are made from high carbon 1095 steel. And while 1095 is a top choice for professional cutlery designed for hard use, it will rust and stain if not properly cared for - especially on the cutting edge and around the laser engraving. It is the user's responsibility to keep the blades properly lubricated and cleaned. We suggest using a dry film rust inhibitor such as TUF-GLIDE or TUF-CLOTH. The ESEE-4 is still a favorite amongst law enforcement and military teams due to its light weight, thin profile and various sheath options.