More recently, modern pistols with polymer-frames have been introduced, such as the 8-shot, .32 ACP Kel-Tec P-32 and 9 mm Luger Kel-Tec P11. The P-11 uses an aluminum receiver inside a polymer grip housing held on with polymer pins. The slide, barrel, and magazine are steel. The standard magazine holds 10 rounds, or 12 rounds in states not limited to 10-round magazines. Both fit flush to the bottom of the pistol. At unloaded, the handgun itself is comparatively light. The P-11 lacks an external manual safety, relying instead on a long and heavy double action only (DAO) trigger pull, which requires 9 pounds of pressure, to prevent accidental discharge. A firing pin spring and low-mass hammer prevent discharge if the gun is dropped. The P-11 will also accept some Smith & Wesson 59 series magazines. An available adapter wraps around the base of 15-round Smith & Wesson model 59-style magazines. The light weight P11s introduced the "subcompact" concept. Prompting, other manufactures such as Glock and Springfield Armory to introduce similar pistols.