1 inch ball mount base consists of a 1 inch diameter ball and a rubberized joint. The ball is mounted at right angles to a 2" x 1.7" square base and is constructed of solid marine grade aluminum with rubber coated ball joints, compatible with RAM Mounts 1"/25mm mounting arms and compatible with all industry standard 1"/25mm mounting arms. There are four pre-drilled holes in each corner of the base. Universal 1.5 x 1.188 (hole spacing) hole pattern, typically compatible with RAM Mount and other industry standard 25mm/1" dual ball seats/arms. Features: 30 x 38mm industry standard 4-hole -Pattern (=AMPS) for use with all industry standard AMPS adapter plates and vehicle specific mounts.Suitable for motorcycle cell phone holder, bike cell phone holder, motorcycle satellite navigation frame, GPS mounted car. Transition: 1cm=10mm=0.39inch Please allow 1-3mm error due to manual measurement. Please make sure you don't mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks very much! Package includes: 1 x Ball Head Square Mounting Base

***It is suitable for Garmin Zumo 400/450/500/550/660, for TomTom Rider 2 / for TomTom Urban Rider GPS navigation holder, for RAM MOUNT, for motorcycle or bicycle holder. *** Easy and convenient to install and remove. ***Suitable for outdoor activities, travel and so on. ***Small shape and compact size, it's easy and convenient for us to take and carry. ***Made of high quality aluminum alloy and rubber, durable and firm, shockproof and stable.