sides in the camper or scout pattern and has an extremely large clevis or bail. The Victorinox Swiss Army Soldier Knife has been issued a National Stock Number (NSN) to be authorized for issue to US service members. This is the first time a US military issued utility/pocket knife that was not manufactured in the United States has been adopted. Miscellaneous designs Another style of folding, non-locking knife is the friction-folder. These use simple friction between the blade and scales to hold the blade in place once opened; an example is the Japanese higonokami. An electrician's knife typically has a locking screwdriver blade but a non-locking knife blade. The two-blade Camillus Electrician's knife (the US military version is known as a TL-29) was the inspiration for the development of the linerlock. A credit card knife is usually a very thin knife that is the shape and size of a credit card, either when folded into a knife shape or unfolded for storage. It is designed to be carried in a wallet along with regular credit cards. Some credit card knives can contain other small tools, such as tweezers, or toothpicks. A ballpoint pen knife is generally a pen with a concealed knife inside, which can be used as a letter opener or as a self-defense weapon. Lock-blade knives Knives with locking blades, often referred to as lock-blade knives or clasp knives, have a locking mechanism that locks the blade into its fully opened position. This lock must be released in a distinct action before the knife can be folded. The lock-blade knife improves safety by preventing accidental blade closure while cutting. It is this locking blade feature that differentiates the lock-blade knife from either the peasant knife or the slipjoint spring-back knife. Locking knives also tend to be larger: it is easier to fit a lock into a larger frame, and larger knives are more likely to be used for more forceful kinds of work. The cost of a locking mechanism is also proportionally less than it would be on a smaller, and generally cheaper, knife. Lock-blade knives have been dated to the 15th century. In Spain, one early lock-blade design was the Andalusian clasp knife popularly referred to as the navaja. Opinel knives use a twist lock, consisting of a metal ferrule or barrel ring that is rotated to lock the blade either open or closed. In the late