The RAM-B-231Z-RVMU consists of a 1" rubber ball designed to sit at right angles to the mounting rail and zinc coated metal u-bolt. The base includes black cover caps to be placed over the exposed ends of the u-bolt. The included composite rail adapter can narrow the rail to a minimum width of 0.5". The mirror base will attach to all RAM 1" diameter ball compatible arms. 

Rail Dimensions:
Accommodates rails from 0.5" to 1" in diameter.

Material: 
Powder Coated Marine Grade Aluminum 

Ball Size:
1" Rubber "B" Ball Size

Note:
The "U" in the part number reflects product packaged in poly bag.