The SG 550 is an assault rifle manufactured by Swiss Arms AG (formerly Schweizerische Industrie Gesellschaft) of Neuhausen, Switzerland; (SG is an abbreviation for Sturmgewehr, or "assault rifle"). The rifle is based on the earlier 5.
Airsoft is primarily a recreational activity with replica firearms that shoot plastic BBs that are often used for personal collection, gaming (similar to paintball), or professional training purposes (military simulations, a.k.a. MilSim, and police training exercises).
A modern combat sport in which participants eliminate their opponents by hitting them with spherical non-metallic pellets launched from a compressed-air gun
Airsoft refers to a class of replica air powered guns that originated from Japan (although the origins go back to the US in the 70s). The power levels are way below those of traditional airguns, but the guns are 1:1 scale copies of original pistols, rather than original designs.
Sig 550
Airsoft replica of Sig 550 assault rifle, made by G&G. Really cool replica, tons of high quality details.
Strobist info:
SB 900 and 2x YN560 and built-in flash, all @ 1/32 from left, top and right. Really simple.
Airsoft - Red Barn (July 2009)
It's a nice long barrel, but I'm not so sure about the tripod on it ...