Articulated Arm, Short, "A" Size
Articulated Aluminum Arm, Length: 3 1/8 inches (80 mm) from base plate to base plate, The arm is 1.75 inches (44 mm) from ball center to ball center, 2 Aluminum base plates with small 9/16" (14mm) balls, weight: 2.4 oz (68 g), Diamond shaped mounting plates are 1.25" (31.8 mm) x 2.5" (63.5 mm).  Mounting hardware not included.  This "A" sized mount is significantly smaller than the large "B" sized mounts below.  The base plates have the same footprint, but the arms are very different.  I recommend this "A" sized mount for light applications.  The "B" sized mounts are nice when a longer reach and more rugged arm is desired (most soaring applications). 

Warning!
Most people find that the "A" sized components work fine for holding a Pocket PC or small FLARM display in an aircraft or automobile.  However, I have received a significant number of complaints about the rubber balls detaching from the bases.  I therefore recommend the larger "B" sized arms for most soaring applications.  In fact, one customer temporarily lost control of his sailplane when his PDA cradle fell off the RAM A arm and jammed the control stick.  The issue is caused by clamping the arm down too tightly on the balls - causing them to deform and separate from the base.  I have never heard of a RAM "B" size arm component failing.