control the shooting distance and retrieve targets for inspection. The target is typically hung from a replaceable hanger attached to a mechanized or motorized assembly that can be placed at varying distances from the shooter, by means of an electrical switch or manual pulley system. Common range shooting distances are 5 yards (4.5 meters) to 33 yards (23–30 meters). Most ranges have minimum shooter-to-target distances, set by the range master, determined by safety considerations. Fees for using indoor public shooting ranges vary widely with local costs, but a typical rate starts at $10 per hour of use, with targets available at a modest charge. Additional fees usually will pertain to damaging target hangers, lights or baffles, up to damaging motors, which may cost as much as $200, per incident. Unlike for outdoor ranges, or for indoor rifle ranges, indoor public handgun shooting ranges are usually run continuously "hot". The only exception is if a target falls from a holder and needs to be retrieved. In this rather rare scenario, some ranges will go "cold", after all firearms are placed on the firing line table with their actions open. Other ranges have a policy that no shooters may go forward of the firing line at any time, so the dropped target is considered lost and must be replaced. Indoor ranges usually have a projectile trap consisting of curved or angled steel plates, shredded rubber, or specially packed and groomed sand, with reinforced baffles attached to the ceiling and walls. The most modern ranges additionally include anechoic chamber technology (foam wedges), or place other sound absorbing materials on walls, floors and ceilings for additional noise reduction. Such ranges also usually have an air-locked corridor for soundproofing, with doors at opposite ends of the corridor. Noise from the range is effectively contained as long as only one door is opened at a time; it is considered a breach of etiquette to open both doors simultaneously. Ventilation is designed to be sufficient in quantity and directional control to reduce concentrations of lead in the air to safe levels in the shooting area. A small group of high volume indoor ranges are now using lead-free and frangible ammunition to create a safer and healthier shooting experience for consumers. The maximum caliber size is sometimes posted on the door of the airlock on each particular range, or in the lobby or ready area if the facility