More than simply a "shortened" Glock 19, design of the subcompact Glock 26 required extensive rework of the frame, locking block, and spring assembly that features a dual recoil spring. Semi-automatic pocket pistols are typically .22 LR, .25 ACP, .32 ACP, and .380 ACP caliber for the older designs. However, newer subcompact designs are also made in 9 mm Luger, .40 Smith & Wesson and .45 ACP. These pistols typically have magazine capacities ranging from 5 to 10 rounds. Pocket revolvers typically range from .22 LR to .38 Special for the older designs. However, the newer designs are also made in .357 Magnum. These revolvers typically hold 5 to 9 rounds depending on the caliber. Derringers such as the older Remington Model 95 were chambered for .41 Rimfire. However, modern derringers are chambered for everything from .22 LR to .45-70 Government, even .410 gauge shotgun shells, with the .22 LR, .357 Magnum and .45 Colt being among the most popular calibers. Today, double barrel derringers are the norm. However, both single and four barrel derringers have also been made. Pocket pistols as the name suggests are usually small pistols carried in a coat, jacket or trouser pocket. They are used for concealed carry by those desiring a discrete self-defense gun, or desiring to carry a backup gun. They are point and shoot pistols, intended for fast one-handed operation. The typical .25 ACP pocket pistol is designed for close range work and has an effective range of about 7 yards (6.5 m). Pocket pistols are typically hammerless designs, made with rounded edges and with few controls, to prevent snagging and to make them easier to carry. Revolvers are also typically hammerless, or have shrouded, or even bobbed hammers, all allowing the gun to be drawn quickly with little risk of it snagging on clothing. The shrouded and hammerless models may even be fired through a coat or jacket pocket. While some of the cheaper semi-auto pistols are best carried with an empty chamber, higher quality pocket pistols are designed to be carried with a round chambered and with a safety engaged (ON). Many older pistols (and even some revolvers) also had grip safeties for additional security. However, the newer double-action-only pistols are made without manually operated safeties, but with a long and heavy trigger-pulls – similar to revolvers.