For divers seeking reliable performance in an uncomplicated air delivery system, the MK11 / S270 is easy to use, compact and durable. The balanced diaphragm MK11 delivers effortless airflow unaffected by depth, tank pressure or breathing rate. A step up from your typical entry-level reg, the compact S270 provides smooth breathing performance in a bulletproof anti-scratch design thatโs able to handle years of hard use.