The EOS flash system is capable of wireless multiple flash control, whereby a master flash unit IR (ST-E2) or RF (ST-E3-RT) transmitter mounted on the camera body can control up to 3 (optical) or 5 (radio) groups of flash units. The Canon EOS 7D is the first Canon body to be able to control Speedlites wirelessly without the use of a Master Speedlite or IR transmitter; four other EOS models, the 60D, 600D, 650D, 70D, and 700D, also have wireless flash capabilities. The 7D is capable of handling three slave groups. The other cameras can handle two slave groups.