Project.21 TrailProject. 21 Trail Helmet The Project. 21 Trail takes the most advanced safety features from our range topping Project. 21 Pro but uses a different padding material and chinstrap clip to provide the best protection at a lower price. Named after the number of vents, the Project. 21 combines massive airflow with the coverage demanded by increasingly technical bike park, all mountain and enduro trails. This airflow gives a cooling effect to keep you