106389
Alternative materials , such as whalebone , cane , gutta-percha and even inflatable caoutchouc ( natural rubber ) were all used for hoops , although steel was the most popular .
 gutta-percha
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 gutta-percha