In airsoft, a sniper rifle is any airsoft rifle that is a replica of a real steel sniper rifle or marksman rifle, and can fire at longer distances and more accurately than most others. Because of the velocity at which they launch BBs, most, if not all, fields have a set minimum engagement distance. The MED dictates is for if any opposing player is within that circle around the sniper, they cannot be shot at unless given a warning that is ignored, but the sniper is usually required to have a back-up airsoft gun to use in the situation that an opposing player gets too close.
As a result of their power, range, and the heavy types of BBs that they use, most Airsoft Sniper Rifles that are worth $80 or more. Scopes are frequently used, and barrels are long. Good secondary weapons are PDW Pistols, SMG's, and, if you are also a primary combatant, a good Assault Rifle. Travel fairly light of you are just a Sniper, but if you are planning on "getting in on the action", then an Assault Rifle and some spare BBs are almost (if not) a necessity.