Say “Happy Birthday” in a big way. A fun addition to your birthday party supplies this Jumbo Inflatable Birthday Cake is the perfect way to decorate for a special birthday party. Blow it up and include in your birthday celebrations at home or at the office. This is just the tip of the ice berg. Find all the party decorations you need on our website to throw one heck of a bash. Vinyl. Inflated 37 x 37 x 6 ft.