The NHL's Department of Player Safety is attempting to explain the different types of hits that constitute a suspension.

On Friday, the department released a detailed video explaining Rule 48 as it pertains to illegal checks to the head and provided four examples from this season's playoffs - two that resulted in suspensions and two that did not - to further explain how the rule is applied.

To begin, Rule 48 was explained in detail. The department noted that just because a player makes contact with an opposing player's head while completing a check, it does not necessarily mean it was the "main point of contact."

In reviewing the four incidents: Drew Doughty's hit on William Carrier that resulted in a one-game suspension, Ryan Hartman's hit on Carl Soderberg that garnered a one-game ban, Ryan Johansen's check to Tyson Barrie and Nikita Kucherov's hit on Sami Vatanen, which both saw no discipline, the video outlines how Rule 48 was applied in each situation.

In the cases that resulted in suspensions, the video suggested that the head was the main point of contact, which is distinguishable by the player's head snapping back upon impact from the attacking player.

Meanwhile, the other two hits saw the attacking player make contact with the head, but only as he followed through after making initial contact with the shoulder or body.

The department concludes the video suggesting the difference between an illegal and legal hit can come down to mere inches and, at the end of the day, their job is to "apply the rulebook as it was written."