Macally Car Headrest Mount Holder for Apple iPad Pro/Air/Mini, Tablets, Nintendo. It has an extendable mount 

secure and stable-strong clamps and also features a support stabilizer arm

car compatibility-any car with round headrest poles 2” to 9” inches wide (most standard cars)

mount directly behind a car seat for a single passenger or in between the driver and passenger seats for multiple passengers The ball-head also allows for different viewing angles and for 360° rotation. 

designed to keep the tablet stable and from bouncing while driving with the strong aluminum shaft

device compatibility (per website specs)-Apple: iPad Air/iPad Air 2/ iPad 2/iPad 3/iPad 4/iPad mini 1/ iPad mini 2/ iPad mini 3/ iPad mini 4/ iPad Pro (12.9, 10.5 & 9.7 inch), iPhone x 8 7 7S 6 6S, Etc. Samsung: Galaxy tab 4/Samsung Galaxy tab 3 kids/ Samsung Galaxy tab 3/ Samsung Galaxy tab a/ Samsung Galaxy tab s/ Samsung Galaxy tab S2 (8.0 inch)/ Samsung Tab Mybat samsung-t355c/ Samsung Tab Mybat Samsung/ Samsung Galaxy tab S2 (9.7 inch)/ Samsung Galaxy Note 8.4 Sony Xperia Z/Z2 tablet

Lenovo: Idea Pad S5000/ThinkPad tablet 10/Lenovo Yoga 10

Acer Icon I a a3-a10

Sony Xperia Etc> Kindle Fire hdx

and most other 7” to 10” devices (3” to 8” wide)