The Interfit INTR1N TTL / i-TTL Studio Flash Remote for Nikon enables complete wireless control of the S1 and S1a monolights from the camera position. It allows for precise power adjustment in Manual TTL and High Speed Sync modes and supports Nikons E-TTL II protocol making it compatible with most Nikon cameras. The remote syncs at up to 1/8000th of second and has an operating range of 320 feet (100m). It also enables remote control of the audible recycle beep and LED modeling lamp. Uses two AAA batteries (not included).