The military mandated a grip safety and a manual safety. A grip safety, sear disconnect, slide stop, half cock position, and manual safety (located on the left rear of the frame) are on all standard M1911A1s. Several companies have developed a firing pin block safety. Colt's 80 series uses a trigger operated one and several other manufacturers, including Kimber and Smith & Wesson, use a Swartz firing-pin safety, which is operated by the grip safety. Language cautioning against pulling the trigger with the second finger was included in the initial M1911 manual, and later manuals up to the 1940s.