A handgun holster is a device used to hold or restrict the undesired movement of a handgun, most commonly in a location where it can be easily withdrawn for immediate use. Holsters are often attached to a belt or waistband, but they may be attached to other locations of the body (e.g., the ankle holster). Holsters vary in the degree to which they secure or protect the firearm. Some holsters for law enforcement officers have a strap over the top of the holster to make the handgun less likely to fall out of the holster or harder for another person to grab the gun. Some holsters have a flap over the top to protect the gun from the elements. Function Holsters are generally designed to offer protection to the handgun, secure its retention, and provide ready access to it. The need for ready access is often at odds with the need for security and protection, so users must consider their needs. Choosing the right balance of security and availability can be very important, especially in the case of a defensive weapon holster, where failure to access the weapon quickly or damage or loss of the weapon due to insufficient retention or protection could leave the user inadequately defended. One of the most important functions of a holster is trigger coverage. Many choose to carry a firearm with a round in the chamber so that it is immediately available to use. Although some gun users believe this to be dangerous, practically all modern handguns are designed to be carried this way, with safety features that are designed to prevent the weapon from discharging unless the trigger is pulled. The use of a holster that blocks access to the trigger effectively mitigates this risk. Holsters specifically designed for the model of firearm tend to perform best in this respect. Likewise, those constructed of more rigid materials better prevent manipulation of the trigger when holstered. Holsters are generally designed to be used with one hand, allowing the handgun to be removed and/or replaced with the same hand. To be able to return the handgun to its holster one-handed, the holster must be made from stiff material that holds its shape so that the holster won't collapse when the object is no longer inside to give it support. Holsters are generally attached to a person's belt or waistband or clipped to another article of