Nailers (also called nail guns) are power tools that drive nails into virtually any material; they are a modern surrogate to the tedious and laborious hammer. Nail guns require the operator to insert a cartridge of specialized nails into the nail gun, and usually can only tolerate a specific range of nail types. After chambering a nail, the nail gun is pressed into the workpiece (as is usually required by the use of a safety-muzzle) and the operator initiates the fun's linear actuator. The actuator drives the nail with force often in excess of a typical hammer, typically inserting the nail completely upon its first strike. Nail guns come in several power options for operation: electrical, electromagnetic, and pneumatic are most common. Hand nail guns operate very similarly to shop-type staplers. Finally, nails guns relying upon combustable gas (butane or propane) or a gunpowder charge (commonly a .22 cartridge) are restricted for nailing procedures in the most rugged of substrates: concrete, stone, hardened steel, etc.