Fastpacking is a marriage of trail running and ultralight backpacking. Fastpackers carry a light pack with essential supplies, including a sleeping bag and tent, or similar form of shelter, if mountain huts or other accommodation are not available. The weight carried will vary but fastpackers aim at no more than 15 pounds (6.8 kg) and some achieve less than 10 pounds (4.5 kg). This activity may be undertaken either unsupported, self-supported, or supported. Unsupported fastpackers have no outside assistance along the way, while self-supported fastpackers will leave caches of supplies along the intended route.