Slap jacks are also known as police leather slaps or blackjacks. While blackjack is a widely used name there is also a fine distinction since blackjacks can also refer to a similar instrument that is made with a round piece of lead as opposed to the flat profile of this device. The other name for it, although not always in use in is beavertail sap. This is actually a more accurate descriptive name since it does have the shape of a flat beaver tail.
A slap jack can be made of different materials but the higher end ones are made of leather. It is a flat poach and like the shape of a beaver tail with the bigger flat side being the clubbing end containing hard material the most favored one being lead. Higher end models have a spring along the entire length of the instrument.
The device is quite convenient since the smaller models are 8 inches in length can be easily placed in a pocket and therefore not that easy to grab by an assailant. Its small size is also like a surprise package since the opposing side may not even know it’s there.
It can pack quite a punch without exerting excessive effort. For law enforcement agents who can still carry this equipment, they are advised to hit at non-critical locations like large muscle areas. A broken bone or skull fracture is possible with this device.
It is very useful in close quarter situations and as a defensive device is used as a weapon that can provide distance between you and the assailant. After striking the assailant it is advised to then run and gain distance away from the attacker. Some have even used this device to ward off dogs.