Fastening by means of enclosed material. 2 variants possible.
Variant A "permanent": by means of double-sided adhesive strips.
Variant B "flexible": by means of post-it-like adhesive, adhesive part attached to the frame, non-adhesive part holds the film to the screen.
For flexible employees with/without privacy protection, I recommend variant B. I use variant A with permanent privacy protection. (It is also removable, but it is more difficult to reuse the adhesive strip)