ASUS Stylus for Transformation (ASUS CHI Stylus) Enjoy natural handwriting input with your ASUS Transformer Book Chi. Compatible Model T90Chi/T100Chi/T300Chi Palm rejection technology prevents accidental touch input 256-level pen pressure for precise, accurate writing A single AAAA battery provides up to 9.6 weeks of regular use Take notes in an instant, you don't even need to pair it via Bluetooth A long-lasting 1mm tip for added durability. Get creative with many popular apps, including Lync, Outlook, Skype, and many more. Two programmable side buttons which can be configured for erase and right mouse click functions.