ikelite housing for leika lx7 & d-lux 6: Dive into underwater photography with this compact yet sophisticated system. Durable polycarbonate and acrylic construction provides a unique view of the camera to ensure correct waterproof installation and confidence underwater. Simply close the two stainless steel locking lid snaps, and see the o-ring form a solid black, watertight seal. Large, ergonomic controls provide access to all important camera functions.TTL or "Through-The-Lens" flash metering means the camera controls flash duration to properly expose an image. Unique intelligence built into the housing communicates to the camera when a compatible external TTL flash is attached and transmits exposure information. This allows the camera to adjust the compatible strobe's power with incredible accuracy. Other benefits include reduced shutter lag, longer battery life, and less heat build up as compared to fiber optic systems which require the camera's built-in flash to fire.