RAM® Diamond Ball Base - A Size
Base with 9/16" Ball

Marine grade Aluminum, 9/16" diameter rubber ball, Diamond shaped mounting plate is 1.25" x 2.5".  The center of the ball is 11/16" above the base of the plate. Weight: 0.7 oz (20 g) Mounting hardware not included.  PDF Drawing

FEATURES:

• Diamond plate features industry-standard AMPS hole pattern and measures 2.43" x 1.31"
• Included A size 9/16" RAM® rubber ball allows for connection to any A size RAM® double socket arm; ball and socket technology allows for near-infinite adjustability
• Made of powder-coated, marine-grade aluminum for durability and reliability in the most demanding environments
• Backed by a lifetime warranty

SPECS:

Hole Pattern:
2-Hole AMPS 1.912"

Ball Size:
A Size (9/16")

Weight Capacity:
.5 lb

Materials: 
Marine-grade aluminum

Weight:
0.07 lb

Warning!
Most people find that the "A" sized components work fine for holding a small phone in an aircraft or automobile.  However, I have received several 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.  I have never heard of a RAM "B" size arm component failing.