The FM2/n has a long-standing reputation for reliability and durability[1]. It has an extremely strong body of copper silumin aluminum alloy[2]. The FM2's film transport consists of high-strength hardened metal gears and moving parts, mounted on clusters of ball bearings. The vertical metal shutter, originally titanium and switching to aluminum during the FM2n life cycle, utilizes precision tapered high-strength blades and oil-less self-lubricating bearings. The mirror linkage uses the same mechanism found on Nikon's professional F2, with some modern improvements designed to further reduce effects of vibration and mirror bounce. The camera features Nikon's famous close tolerance assembly and minimal space lubrication, meaning that it will reliably operate in temperature extremes of −40 °C to +50 °C. The FM2 is a mechanically-controlled manual focus SLR with manual exposure control. It is operable without batteries and only needs the two S76 or A76 batteries, or one 1/3N battery to power the light meter, which consisted of an internal 60/40 percent centerweighted system linked to a center-the-LED exposure control system. The exposure control system used vertically arranged +/o/– light emitting diodes (LEDs) on the right side of the viewfinder to indicate the readings of the meter versus actual camera settings.