The production's home base is in the United States (the Louisiana Bayou, Florida ( Everglades and Seminole County) and Alabama). Main article: List of Naked and Afraid episodes Production Locations Before and after weight measurements are also revealed at the end of an episode. Naked and Afraid computes and then updates the cast members' PSR (Primitive Survival Rating), which is based on predictions and observations of survival fitness in skill, experience, and mental strengths. Viewers are updated throughout with statistics including how many days have passed, the time, and the temperature. If they do not tap out, they must arrive at the designated extraction point on the final day to be picked up by a helicopter or boat or other vehicle suitable to the environment. A team is allowed to "tap out" at any point during the 21-day challenge. At the beginning of the fourth season, the survivalists were given a third "surprise" item. Castmate Alison Teal reports that she was granted an "emergency" tampon. There is a camera crew who are not allowed to intervene except for medical emergencies when it is "absolutely necessary". Each survivalist is allowed to bring one helpful item, such as a hatchet or a fire starter. They all wear identical necklaces with a center bead which is a microphone with a wire that connects to a wireless audio transmitter hidden in the satchel. They are provided with rough cross-body satchels containing a personal diary/camera for use when the camera crew is not there at night, and a map. The events of each couple's quest play out in a single episode.