The Tuff TTL Receiver for Nikon Flashes works with the optional Tuff TTL Trigger to allow you to wirelessly trigger a Nikon flash with i-TTL compatibility. The Tuff system uses a 2.4 GHz frequency and has a range of 656' for wireless communication. Additionally, the receiver has a Mini-USB port for external power options and firmware updates as well as a standard 1/4"-20 threaded mount. The receiver features a removable silicone casing for durability and it connects to the trigger via Digital Channel Matching for a quick and reliable connection that avoids interference with other units. It also allows for both TTL and manual flash settings and runs on two AA batteries.