The round plate contains two mounting holes at 180 degrees and three mounting holes at 120-degrees. The 1.5" x 4.5" rectangular plate contains a 4-hole pattern compatible with Hummingbird 8,9 and 10 models. The rubber ball and socket technology provides shock and vibration damping, and allows for near-infinite adjustability so you can position your device at the perfect viewing angle. 

Product Details 

• Overall height: 7.875" 
• Top plate: 2" x 5" 
• Bottom plate 3.68" Diameter 
• Ball size: D size (2.25")
• Weight: 3.0lb