City Scene Design-A-Room Background. 8 ft. x 30 ft. (2 pcs. per set) Plastic Decorate your event faster than a speeding bullet with this easy-to-use background. Perfect for superero parties and events, this plastic background will set an epic scene and make a great photo backdrop. Discover even more superhero party supplies on our website. Plastic. (2 pcs. per set) Assembled, 8 ft. x 30 ft. Simple assembly required.