The RAM Quick-Grip XL Phone Mount with RAM Vibe-Safe & U-Bolt Base - Short (RAM-B-149Z-A-PD4-462) is a combination of the RAM Quick-Grip XL Phone Mount and the RAM Vibe-Safe - our vibration damping accessory is designed to protect electronic devices from a wide range of vibration frequencies. The RAM Vibe-Safe is based on an NPT connection point and boasts the versatility to rotate between portrait and landscape while keeping your device secure in rugged environments. This product includes one (1) short B size arm and one (1) RAM U-Bolt Base that accomodates rails from .5" - 1.25" in diameter. The holder is compatible with handheld devices that will fit the dimensions listed below, it is important to verify the dimensions of your handheld device with a case/sleeve/skin when determining the overall size.