Features: The new RF-603 II is improved version of RF-603, it is a remote shutter release as well as a multi-functional flash trigger which can synchronously trigger flashes and studio strobes. Through the transceiver based system each item can be used flexibly as trigger or receiver. Only 2 AAA batteries are required as power source for each item. The 2.4GHz wireless frequency is suitable in most countries and guarantees high speed, distance and stability. Within capacious areas, the remote control distance may reach to 100m. The synchronization speed can reach to 1/320, depending on the situation. Improved features: 1. Hot shoe locking system to prevent from slipping off 2. Switch on side for easy operation 3. Enhanced self-detecting system Functions: Supports single contact triggering. Can achieve wired and wireless remote shutter release function. Flash Trigger: to fire the Flash Speedlite; to fire the Studio Strobe light (You need to purchase an extra 6.35mm cable to fulfill this function). You can use ABOVE TWO FUNCTIONS simultaneously. This listing is for C3 version: Replacement For Canon 1D 5D 7D 10D 20D 30D 40D 50D Specifications: Type: FSK 2.4GHz wireless remote sustem Transmitter distance: 100M Channel: 16 channels Release: half-way press, full-way press Receiver interface: one is 2.5mm socket Studio flash light interface: Standard PC socket Battery type: 2 * AAA (not included) Stand-by time: Up to 45hours (TRX); up to 400hours (TX) Item size: 80.7 * 31.3 * 25.9mm / 3.2 * 1.2 * 1.0in Item weight: 44g/ 1.6oz (each) Package size: 16 * 9 * 4.5cm / 6.3 * 3.5 * 1.8in Package weight: 177g / 6.2oz Package List: 1 * Tranceiver 1 * Receiver 1 * Shutter connecting calbe C3 1 * Manual (English)