Improved from the original Crossbow Unloading Bolt (CUB), TenPoints CUB Bolts with Omni Nock can be used to unload most crossbows, including reverse draw and extremely narrow crossbows. These safe, cost-effective and single-use bolts are made of biodegradable polymer, so they decompose over time. Per 6. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Biodegradable Bolts.