Less commercially described, Zytel is a nylon material often reinforced with fiberglass for additional toughness and resistance to solvents. It holds up well in extreme conditions and is extremely tough and resists corrosion. It can survive for long periods in salt-water conditions which makes it a good choice for knife handles used by the Navy SEALs. Another feature important to the SEALs is that it does not become slippery when wet.

Zytel knives have been created for the Central Intelligence Agency for covert military operations and continue to be used by various agencies for covert (black) ops. In addition to the SEALs, Zytel knives are also used by the Green Berets.

Zytel is extremely popular for knife handles, including knives made by Gerber, Benchmade and SOG, because it is extremely light-weight; it weighs less than one-fourth as much as steel. Other reasons Zytel is one of the most popular materials for knife handles are that it doesn’t expand or contract in heat or cold, and it won’t become scratched or discolored with heavy use. Zytel naturally has a slightly textured surface, but knife companies will usually add more texture to help gripping and holding.

For manufacturers, Zytel is popular because it can be injection molded which helps keep costs down even though it is more expensive than some other materials. It is also available in many different grades.

It’s little wonder Zytel was chosen for the handles of the SOG SEAL Knife and the SEAL Pup. It was created for both strength and durability. It has proven to be both durable and maintenance free, and it definitely makes a knife more affordable. Because of its many features and affordability, it is likely to reaming a very popular material for knife handles for both every-day users and well as Navy SEALs and other special forces for years to come.

There are two features necessary for a sharp edge. The first is the ability to make it and the second is the ability to maintain it. It is very difficult to produce a sharp edge on soft metal because of its tendency to deform and round off. Of course high hardness means it will hold an edge fairly well, but it is more difficult to get an edge on it in the first place. The primary goal of 440A steel is stain and wear resistance rather than holding a high performance edge, but that doesn’t mean it can’t be used for a quality knife blade. Proper heat treating of 440A can result in the high hardness necessary for a blade.

There are several main “ingredients” in stainless steel (in fact in all steels.) Each one gives the metal certain properties.

Carbon
Steel is an alloy of iron and carbon. The amount of carbon in a steel determines its hardness. 440A is between 0.6 and 0.75% carbon. Compare this to the 0.3 to 0.25% carbon in steel in the 300 series. The high carbon content is instrumental in giving 440A steel its hardness.

Chromium
The presence of chromium is what distinguishes stainless steels from other corrosion-resistant materials. Due to its strength and its high resistance to corrosion, chromium is often used in plating and metal finishing. In stainless steel the chromium forms a protective layer called a passive layer or passive film which reduces the corrosion rate.

Nickel
Nickel promotes the resistance to corrosion, especially pitting corrosion. Pitting corrosion can occur when stainless steel is subjected to high concentration of chloride ions (for example, sea water) and moderately high temperatures. Nickel is also a mild strengthener. Stainless steel contains less than 2% nickel.

Molybdenum
Molybdenum is important for giving strength to steel at high temperatures. It is also resistant to corrosion. 440A stainless steel contains a maximum of 0.75% molybdenum, but even that small amount has significant effects on corrosion resistance.

Other elements in 440A stainless steel are manganese (1% maximum), phosphorus (0.04% maximum), silicon (1% maximum), and sulphur (0.03% maximum.)

Although there are higher quality steels, the compromise between price and performance make 440A stainless steel a popular choice for knife blades. It’s resistance to salt water and other corrosion makes it a good choice for the SEALs and other special forces.

There is no “one” knife used by all Navy SEALS. There are, however; several knives of such quality that they are used by many SEALs.

These knives are among the toughest mass produced knives available.

Navy SEAL Knives

The United States Navy SEALs are one the world’s most elite combat units. The training lasts 11 months, and puts recruits through some of the most grueling challenges imaginable, including “hell week” during which trainees get a total of about 4-hours sleep.

After training, SEALs perform some the most dangerous and secret missions required. When you’re miles away from any possible re-supply, and the only things between you are certain death is your training and your equipment, you have to have the best of both. One of the most important pieces of equipment is a knife.

Mission Knives’ MPK Ti (Multi Purpose Knife - Titanium) is an impressive knife. The blade is titanium and very rugged. According to Mission Knives, it “survived continuously under seawater four years without any signs of rust or corrosion.” The handle is made from Hytrel, a DuPont product known for its toughness, broad temperature use, and chemical resistance. It is reinforced with the ballistic fiber Kevlar (another DuPont product.)

The sheath is also made from Hytrel/Kevlar and offers a variety of strap down methods.

The MPK Ti is available in 10 and 12 inch models. The suggested retail price for the 10″ model is $426. The 12″ model is $426.

SOG’s SEAL Knife is a popular knife made from AUS 6 steel hardened to 56-58 RC. The 7″ blade is powder coated to reduce glare. The handle is made from DuPont’s Zytel.

The sheath is Kydex, a durable alloy manufactured by Kleerdex. It features a groove which allows the knife to cut cord or rope without being unsheathed.

In a head-to-head comparison the SOG SEAL was outperformed in almost every category by the MPK Ti, but at an MSRP of $165.00 the SOG SEAL is much more affordable.

The SEAL Pup is a smaller version of the SOG SEAL. It has an overall length of 9″ and a blade length of 4.75″. Like the SEAL, the blade is partially serrated AUS 6. The Pup comes with a standard nylon sheath, but a SOG Groove%u2122 Kydex sheath is available for an additional $25.00.

At $93.00 it’s a nice knife at a fair price, especially if you can pass on the sheath upgrade.

Aqualung Master Dive Knife - Recommended in the U.S. DIVERS MARITIME OPERATIONS EQUIPMENT GUIDE

A favorite among the SEALs. Its heavy steel butt is great for hammering. The 7″, partially serrated, 420 stainless steel blade is thick enough to use for prying.

At $59.95, you can’t go wrong.