Transport helicopters are operated in assault, medium and heavy classes. Air assault helicopters are usually the smallest of the transport types, and designed to move an infantry squad or section and their equipment. Helicopters in the assault role are generally armed for self-protection both in transit and for suppression of the landing zone. This armament may be in the form of door gunners, or the modification of the helicopter with stub wings and pylons to carry missiles and rocket pods. For example, the Sikorsky S-70, fitted with the ESSM (External Stores Support System), and the Hip E variant of the Mil Mi-8 can carry as much disposable armament as some dedicated attack helicopters.