A knuckle thrower for a railway coupler assembly, the thrower having a knuckle actuating leg, a leg lock seat, an upper pivot structure, a lower trunnion, and stress relief feature for relieving stresses imparted on the thrower, which, according to some embodiments may include a recess provided in the perimeter wall thereof, and one or more supporting ribs. The locking mechanism locks an electronic device so that it cannot be removed when the lock-releasing member is in the locking position and unlocks the electronic device in response to an operation of moving the lock-releasing member from the locking position to the lock-releasing position. Tightening means, exterior in part to the interior chamber, move from a first position wherein the mirror head may turn relative to the pole and into a second position to orient the mirror head into a desired position and fixedly clamp the mirror head in that position.