Keyguard for the Acer Chromebook Spin 311 US English version.
No attachment method is provided with this keyguard. You'll need to attach it yourself with something like double-sided tape, Velcro, or mounting putty (Blu Tack, etc.)
The default material is 3/16" clear acrylic. 1/8" thick materials are available for users who require the openings to be shallower. There are also a number of 1/4" thick materials available.