The RAM-B-166-UN7U consists of a 3.3" twist lock suction cup base, double socket system and universal spring loaded X-Grip® holder for cell phones. The suction cup, twist lock base is designed to have a strong hold on glass and non-porous plastic surfaces. The included X-Grip® cradle has a clean and clever four leg design that sports great holding power without hiding your phone behind foam pads and plastic. The spring loaded X-Grip® holder expands and contracts, allowing for a perfect custom fit of your cell phone. The perfect compliment to the modern sleek interior of today's vehicles, the RAM X-Grip® is the cell phone holder evolved.The X-Grip® 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.