The RAM® Handlebar U-Bolt Base (RAM-B-231U) is a rugged mounting base designed for rails 0.5" to 1" in diameter, with an integrated B size rubber ball. This base is compatible with all B size socket arms. The stainless steel u-bolt is secured to rails or handlebars by two nylock nuts and comes with an optional composite adapter that narrows the attachment to the minimum compatible rail width of .5". Cover the end of the u-bolt with the included two rubber caps, ensuring no clothing or equipment get snagged.