The MCH is now fully programmable, by the end-user. This allows you full control over the output of the flashlight. You can change the programming anytime you want. Features 5 modes, programming is incredibly simple and intuitive; each light ships with the full ND Protection package and the user can now configure the tail cap for their respective needs; 18650 single output option: 40,000 Candela/1700 Lumens/65 minutes; two CR123A output 30,000 Candela/550 Lumens/60 minutes; you are able to easily change the battery from the light head side of the MCH. The positive end always goes to the front of the light. And there is reverse polarity protection built in just in case and IPX-8 waterproof rating. Fully submersible to 100 Ft. for 24 hours.