Place 4 frozen 6 -8 pound rock lobster tails on cutting board. With a sharp knife, cut down through the center of hard top shell, cutting through meat, but not through under membrane Spread open, butterfly style, so that the meat is on top. Cover tail fans with foil. Brush the meat with melted butter, Broil 4 inches from heat about 17 minutes. Brush  often with butter. Meat is done when it loses its translucency and can be flaked with a fork. Serves 2