1 Merino is one of the softest types of wool available, because of finer fibers and smaller scales.  Merino has an excellent warmth-to-weight ratio compared to other wools, in part because the smaller fibers have microscopic cortices of dead air, trapping body heat similarly to the way a sleeping bag warms its occupant.
Transistorâtransistor logic (TTL) is a class of digital circuits built from bipolar junction transistors (BJT) and resistors.
A-TTL is an initialism that stands for Advanced-Through The Lens flash metering. As with ordinary TTL flash exposure systems, a sensor inside the camera reads the amount of light being reflected off the film during the exposure. When the sensor determines that the exposure is sufficient, it terminates the flash pulse. A-TTL, first seen on the T90 (which predates the EOS family), is a flash exposure system that adds a brief preflash during exposure metering when the camera is in the programmed exposure (P) mode.