The Speedlite 580EX II Flash, features a host of improvements over its predecessor, including a metal hot shoe with an improved locking mechanism for added durability, an external metering sensor for non-TTL automatic flash exposure control and a PC socket for use with non-dedicated slave triggers. Fully compatible with all EOS SLRs, the new Speedlite 580EX II is sealed for dust and moisture resistance, making it possible for users of EOS-1 class digital SLRs and many L-series EF lenses to use flash safely when shooting in dusty or wet environments.