Metro travelers are advised to keep a close guard on their belongings, as petty or opportunistic theft is somewhat of a problem in lines that connect some districts to the center of Santiago. This is most apparent with passengers who reverse their backpacks so that the bag is across the stomach, to ensure that no one can pilfer the pockets out of sight. Metro is part of Red Metropolitana de Movilidad, the integrated public transport system that serves the capital using also feeder and main bus routes. Red works with an integrated fare system, which allows passengers to make bus-bus or bus-metro transfers on a two-hour time limit from the first trip (maximum of two changes) using a contactless smart card called "Bip! card". Bus-to-bus, metro-to-bus and metro-to-train transfers do not cost extra. Bus-to-metro transfers costs $20 (approx. US$0.03) during "Horario Valle" (low-use hours) and $80 (approx. US$0.12) during "Horario Punta" (rush hour). Bip! cards are available in all the ticketing offices in every station at a cost of $1,550 (approx. US$2.23), with a minimum first charge of $1000 worth of credit (approx. US$1.41). Tickets are sold from 6:00 to 23:00 Monday to Friday, 6:30 to 23:00 on Saturdays, and 8:00 to 22:30 on Sundays and holidays. Cards can be topped up to $20000, and the credit only expires if the card it is not used in two years. Metro also used to sell single-trip, Metro-use only tickets, but they went out of circulation in early 2017. Fares depended on the time of the use of the system. The cost of a ticket in the "Horario Punta" (rush hour, 7:00–8:59 and 18:00–19:59) was $700 (approx. US$1.01); in the "Horario Valle" (off-peak hours, 6:30–6:59, 9:00–18:00, 20:00–20:44, and all day on weekends and holidays) was $640 (approximately US$0.90); and in the "Horario Bajo" (low-use hours, 6:00–6:29 and 20:45–23:00) was $590 (approximately US0.85).