Lazer Nirvana White/Black, (LG / X-LG) (57-61cm) Helmet, w/visr Lazer Nirvana White/Black MTB Helmet Large/X-Large 57-61cm. Patent-pending Rollsys fit system is easily adjustable and very comfortable ! Rigidity Brace System: Reinforcements for a superior helmet resistance against multiple impacts. Internal Ventilation channels for optimum airflow with Antimicrobial and temperature regulating padding system ! Super Light Weight Only 260g ! 21 Large Vents with Integrated Tech Visor !