Nexus 9 is manufactured by HTC. It features an 8.9″ IPS LCD display with 1536 x 2048 resolution. It’s powered by an Nvidia Tegra K1 dual-core 2.3GHz processor and 2GB of RAM. Internal storage is available in either 16GB or 32GB. The Nexus 9 features a large 6700mAh battery, and 8MP camera, with 1080p video recording, along with a 2.1MP secondary front facing camera.
Nexus 9 runs on stock Android 6.0 Marshmallow. But if you want to try a custom ROM on this device, CyanogenMod team have created a CM 13 ROM. An official nightly with very few bugs is available for this device. If you want to install it, a detailed guide is given below.