Stretch Armstrong keeps best at room temperature. Stretch Armstrong is made of latex rubber filled with gelled corn syrup, which allows it to retain shape for a short time before shrinking to its original shape. An estimated 67 different versions from Japan, Germany, Italy, France, Australia, and other countries released Stretch Armstrong variations between 1976 and the 1990s. The last two were filled with a granular solid in place of the viscous liquid found in the other figures. A vacuum pump, which attached to the heads of these figures, removed the air from within, which "froze" the toy in its stretched position.
Natural rubber refined into rubber ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for marketing. Natural rubber is used extensively in many applications and products, either alone or in combination with other materials. In most of its useful forms, it has a large stretch ratio and high resilience, and is extremely waterproof. The major commercial source of natural rubber latex is the Pará rubber tree ("Hevea brasiliensis"), a member of the spurge family, "Euphorbiaceae". This species is preferred because it grows well under cultivation.