Canon's Speedlite 600EX-RT is engineered to provide a new level of performance and reliability for professional flash photography with today's most advanced DSLRs. With wireless two-way radio communication, the Speedlite 600 EX-RT allows photographers to expand their creativity using wireless speedlites with the reliability of radio triggering. The Speedlite 600EX-RT offers an expanded zoom range and a higher guide number, plus a number of improvements over its predecessor in both operation and feel. It features a new dot-matrix LCD panel for display of all pertinent shooting information, backlit controls plus an internal sound generator. Reliability is ensured with improved hot shoe contacts and improved flash head durability.