Drop arm or tripod turnstiles are a type of waist-high turnstiles. They usually consist of three horizontal arms, which rotate as people pass through. However, drop arm turnstiles with single or double arms are also common. You can see these in bus terminals, metro stations, parks, stadiums, and museums. They are often used in combination with an automated coin and bill acceptor or ticket checking system. Browse TURNSTILES.us selection of pedestrian traffic control devices made in the USA.