A gasket may have at least one metallic layer with at least one combustion gas through-opening and at least one fastener through-opening. Also, the gaming machine of the present invention has one or more bonus games, and a player can change a bet amount at any time during the course of said bonus game. When an angle of the projecting device is adjusted, the signal generator generates and outputs a corresponding adjusting signal serving as a basis for the keystone correction according to the electric property of the adjustable part.