Sunpak DigiFlash 2800 Electronic Flash Unit (Nikon i-TTL) for Nikon D40, D60, D3000, D3100, D5000, D90, D300, D300s, D7000 & D3 Digital SLR Cameras Small and light weight body requires only 2 AA batteries (batteries included) Guide Number (ISO 100): 100' (30m) TTL signals are automatically recognized just by mounting and turning on TTL automatic check function &amp; EV adjustment buttons enable free operations 90 Degree Bounce Head &amp; Auto Focus Assist Light supports focusing in low light situations