The ornamental design for a balloon for decoration, as shown and described.
1. Balloon for decoration
1.1 : Perspective
1.2 : Front
1.3 : Back
1.4 : Left
1.5 : Right
1.6 : Top
1.7 : Bottom
Materials include vinyl and a synthetic resin; the subject design is used for interior decoration, and a decoration of garland is inside a transparent outer balloon to be filled with a gas; fig. 1.1 shows a perspective view of the subject design; fig. 1.2 shows a front view of the subject design; fig. 1.3 shows a rear view of the subject design; fig. 1.4 shows a left view of the subject design; fig. 1.5 shows a right view of the subject design; fig. 1.6 shows top view of the subject design; fig. 1.7 shows a bottom view of the subject design.