Inflatable Reindeer - Vintage HEAVY rubber Made in Japan

This cute inflatable reindeer made of HEAVY rubber was bought at an estate sale and don't know much about him. He stands approx 23 inches tall, has a metal air plug (not sure if original but it works great) and holds air well....I had him inflated for two days without air loss. To tell you how heavy of a rubber he is made from, he weighs 197 grams (approx 7 ozs). Stamped with; Shecial (Special??) Joshin Made in Japan A19. Any info anyone can share would be appreciated. Thanks