The RAP-B-138-UN7U consists of a 2.5" diameter round base featuring the universal AMPS hole pattern, medium length composite double socket arm, and the popular spring-loaded RAM® X-Grip® phone holder. The RAM® X-Grip® features an 'X' design that expands and contracts to provide a perfect fit for your device – even if it's in a case. Made of marine-grade, stainless steel components and high-strength composite, this version of the RAM® X-Grip® fits phones ranging from 1.87" to 3.25" in width and keeps your device completely functional and accessible. RAM® ball and socket technology allows for near-infinite adjustability to achieve the ideal viewing angle – while also extending the life of your phone by providing shock and vibration damping. For outdoor applications, the RAM® X-Grip® includes a device tether that is recommended for added security and peace of mind.