Ram Short Arm Mount A LengthLow profile, big adjustability. The RAM Short Double Socket Arm (A Length) is the most compact B size arm in the RAM lineup, giving you 2. 42" of overall length with a 1. 75" socket to socket span. Perfect for riders who want a tight, streamlined mount without sacrificing adjustability. Designed for use with any B size 1" RAM ball base, holder, or adapter, this short arm uses the patented ball and socket system to provide near infinite viewing angles.