The suspension, a first for Hendricks in his 444-game career, will cost him $29,838.72, per Chris Johnston of Sportsnet.
As explained in the video, the "forceful" hit caused a "dangerous and violent collision with the boards," and "at no point [was] Ekblad eligible to be checked by Hendricks on [the] play" because he made "no sudden movements just prior to or simultaneous with contact."
The final explanation is the main reason the hit was considered illegal.
If Hendricks serves the suspension without appealing, he will return at an interesting time, per Tim Micallef of Sportsnet:
The Oilers can't afford any setbacks at this point, considering they have the third-fewest points in the league. On the other hand, Ekblad and the Panthers sit atop the Atlantic Division with 56 points.