U-Bolt Mount, Plastic, For mounting a 1 inch "B" size ball to a 3/4" to 1" Diameter Rail
The plastic base has a 1.0 inch diameter Rubber Ball designed to sit at right angles to the rail. Fits a circular post or handlebar with diameter from 3/4 to 1 inches.  The entire assembly is completely rust proof.  This unit is very light when compared with the RAM-B-231U but since it is made of plastic it is obviously not as rugged.  I don't think I would trust it to support my expensive GPS on my bicycle.  I fear that the repetitive shocks would fatigue the unit and cause it to fail.  Weight: 0.7 oz (20 grams)