Many modern specialty matches have been devised, with unique winning conditions. The most common of these is the ladder match. In the basic ladder match, the wrestlers or teams of wrestlers must climb a ladder to obtain a prize that is hoisted above the ring. The key to winning this match is that the wrestler or team of wrestlers must try to incapacitate each other long enough for one wrestler to climb the ladder and secure that prize for their team. As a result, the ladder can be used as a weapon. The prizes include – but are not limited to any given championship belt (the traditional prize), a document granting the winner the right to a future title shot, or any document that matters to the wrestlers involved in the match (such as one granting the winner a cash prize). Another common specialty match is known as the battle royal. In a battle royal, all the wrestlers enter the ring to the point that there are 20-30 wrestlers in the ring at one time. When the match begins, the simple objective is to throw the opponent over the top rope and out of the ring with both feet on the floor in order to eliminate that opponent. The last wrestler standing is declared the winner. A variant on this type of match is the WWE's Royal Rumble where two wrestlers enter the ring to start the match and other wrestlers follow in 90 second intervals (previously 2 minutes) until 30-40 wrestlers have entered the ring. All other rules stay the same. For more match types, see Professional wrestling match types.