JBL has developed a proprietary compounding process and latex formula that delivers unparalleled modulus strength. It is called Nitro Rubber. This elastic super material is what puts Nitro Bands in a league of their own. Nitro Bands feature an exponential power to stretch ratio that delivers unmatched contraction. The result: maximum shaft propulsion. This means your shot goes from A-to-Fish before your target knows what hit it. Pull the trigger and let Nitro Bands do the rest. In addition to exceptional performance, Nitro Bands are designed for long lasting use. Nitro Rubber is infused with special anti-oxidants to help protect against harmful UV rays. Wishbones are made from 302 stainless steel wire for extreme strength and durability. For maximum life, we recommend rinsing bands with fresh water and storing them in the provided resealable bag or in a dark and dry place.